Sims 3 and other expansion packs

No never played those before.. I always wanted to though D:

Try it , its pretty fun

I've been trying to make Sims 3 clothing and things, like the custom content you download, trying to look for a good program to do it on but the tutorials I've seen look so complicated and time-consuming. I think I'll leave that to the side for now. But just overlaying a plain t-shirt with a flower, or something, looks pretty straight forward. Has anybody made custom content before?

I only ever played the sims on my ps2 and on my cousin's xbox360.