Hey fierce, its easy. If youre making graphics pixel by pixel its really easy. just color fill the background part that you want to be invisible with a color that you dont use in your actual sprite...
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and then in your paint program you should have a transparency option somewhere for paletted images. it should let you select the palette index you wish to make transparent (or background color) and then save it in a format that supports transparencies.
and you get your transparent image