As I'm sure you know, there are DOZENS of ways to do this type of game, and it would vary by your expertise (if you had some), however your original list of "tech to use" was a sound set of tech that is A) used for this type of thing a lot .. and B) used TOGETHER with each other a lot ... and therefore C) has a LOT of online help available ... so it is a good choice.
Don't let yourself worry too much about doing things the RIGHT way at this point ... until you get something at all satisfying DONE, BY YOUR OWN HAND ... don't judge how it should be done, just try to do it BY ANY MEANS POSSIBLE.
For the client UI (in a browser) you are going to pretty much have to use either: HTML, CSS and Javascript ... or else Adobe Flash, which requires the client to have installed the flash player to play your game ... those are really the only 2 options ... both are great ... 5-10 years ago most the simple cool games would have been Flash (which uses the language ActionScript), but recently HTML (XHTML or HTML 5 specifically) is getting to be more popular. Neither one is a bad choice at all .... just spend 2-10 days trying the tutorials of 1 and see how it goes. If you hate it ... try the other ... but after you've tried both, if you hate them both ... pick one anyway.
For the server side there are too many good choices to list. But PHP and MySQL would have been the best cheap indie choice 5-10 years ago for sure, and is still fine.
For Data - You can now use ANY of the SQL backends (MySQL, PostgressQL, MS SQL Server Express or SQL Anywhere, SQLlite) or even NoSQL options like MongoDB (and many others I've never used). That said, the issue is not which DB you pick, that won't matter (except of course the choices between SQL based and NON-SQL based, which does matter). The issue will be - learning RELATIONAL DATABASE MODELING / DESIGN well enough to organize your data in a way that doesn't suck for your game / goals. Given a decent data model, I can use ANY of the existing tools with almost no issues. So my recommendation is A) pick a tool (like MySQL) and use it ... but mainly just use simple standard ANSI SQL - don't bother learning any more custom MySQL specific stuff than you absolutely have to.
For Langauge - You can use ANY decent server supported languages. 5-10 years ago that would be either PHP, Perl, Python, ruby ... or Java or C#. Today it's basically the same list ... except most people don't use Perl for server code much anymore. PHP is extremely easy to use for small programs. Python and ruby are similar but harder to start with ... however better for bigger programs. C# (and probably Java) are great programming languages for programmers ... which I am, so I prefer C# ... but less good for people who aren't professional programmers. If you want to learn programming in general, I recommend C#, PHP, Python or Javascript as good starting points ... but if you want to get stuff done on a webgame quickly .. I'd skip C# (even though its my personal favorite).