I mean even though they are all artist they still have strength and weakness...

The tasks should be discussed with the team. Identify what each artist's strengths are, and discuss the task list fully with them. Identify gaps (tasks that don't match up with any of your artists' strengths) and discuss solutions. In short: involve them in the task assignment decision process.

I know that we should discuss...

but if no one is managing the to do list and other find that he is doing more work than the other

it feels like the team gonna collapse

Everyone is selfish and wants some part they own for themselves

so I perhaps think about sharing it per stage

so each person got a stage they can own

and try to keep the art style as similar as possible

I want to tell them the pro and cons in the way we share workloads

can somebody who have done this kind of management give me advice ?

I kinda need that right now

can somebody who have done this kind of management give me advice ?

I have only managed professionals who I was paying to do the work. I also was not the lead programmer (I was the producer). You need a producer and you need to pay your people and if they act like children, you should replace them.

The fact that this won't be a commercial product

it won't be anything big and all

and it's still my first project

I doubt I could pay anyone

ok, I failed about 2 times in the past perhaps this is my third try and still my first project

we make this game base on our interest ...

I am not paying anyone anything,,

I guess I will be doing trials and error for now,,

Trying which method best suited my team management

anyway, I am still open for advice

If your people are all volunteers, and if you are the project leader, then you need to find out what motivates each volunteer. Some may work because they like you or your concept. Some may work because they want your game to be published (hoping to get money some day). Some may work because they want your game to be published so they can point to it and say "I worked on that."
Once you know what motivates each person, you can leverage that knowledge to keep that person working effectively.
But that's not your question, is it -- you're looking for how to divvy up the tasks. So first find out what motivates each volunteer. Once you know that, you can leverage that knowledge while assigning tasks.
You should get a good book on how to manage people.

On the issue of distributing tasks, one fairly effective technique is simply to let them divide the work themselves. There should be tables or spreadsheets or tracker apps that production, design, and discipline leads fight over and prioritize. Assuming clear communication and discussion everyone should have a shared understanding of the work. Let everyone pull from the highest priority tasks, they know their skill sets and experience better than you. It is rare that a specific person must be assigned to a task, and those few key tasks are easily assigned in advance.

On the issue of consistent art, for art tasks you need an art lead and plenty of concept art. The concept art and design docs should give more than enough info on style (else they are incomplete), and the art lead should verify every model and UI screen as part of the process; no signoff means the task is unfinished and stays on the list.

Left unasked are how to turn designs into actions, how to create and identify tasks, how to reduce/agglomerate tasks into reasonable chunks, how to verify quality of the work, how to motivate people, how to lead, and how to manage people. Those are much broader questions.

We struggled with this until we took a crash course on agile development. We've now been practicing agile for over a year and our productivity has been through the roof. There are lots of resources on the web explaining how agile works. I would suggest trying it out using sticky notes on the wall, or using the free trial of either AgileZen (the one we use) or Trello.

I really think that management shouldn't be a big issue when I keep the team small,,

and also Managing things isn't really the thing that interest me in game making process

They are important.... so I need to do that..

Some of the people whom I have worked with in the past doesn't use computer often so I think yes sticky notes and paper are better for my team...

ok here is how it usually goes

They draw things on paper base on the description given to them

send them of to me,,

me or one of my friend trace it and add some basic colour

and hope that someone will animate that

because Animating is a painfully long process for a newbie

I am a programmer and I've tried web design before so I can basically trace

I will try to find out more about Agile Development

I know Trello for a long time it's just that they rarely use computer so it's out of option for now...

and these unasked broader question

Left unasked are how to turn designs into actions, how to create and identify tasks, how to reduce/agglomerate tasks into reasonable chunks, how to verify quality of the work, how to motivate people, how to lead, and how to manage people. Those are much broader questions.

I think I might ask them in the future,

I just think that if I ask now, there will be a swarm of article to read and perhaps I'll back down out of depression ....

please pardon my english...

thanks for all your reply and sorry for the late reply

Some of the people whom I have worked with in the past doesn't use computer often so I think yes sticky notes and paper are better for my team...

The paper system is useful for people who enjoy computers and use computers for everything else. He's just talking about the task-tracking method favored by the management system he's talking about. But for a team that is not co-located, a paper scrum board may not work.