Trying to put up a new theme

because my XP one sucks

but every time I download one, I can never put it on

Any help?

What do you mean by you can't put it on? Can't find it?

No, I mean, I downloaded a few and I tried to browse for them through properties

but I think they're the wrong file type

If you know the problem...

But I don't know how I would find the solution

I think there might be system requirements

seeing as how my computer is 02, and as slow as fuck

I might need to download some stuff