Can somebody help me, cause it's already allowed in friendster to link a stylesheet but then I really dont know how to change the entire background

using the usual

body
{ background-color:#ff6699;
blahblahblah}

because it doesnt work somebody told me I should learn more with css and I really need your help...I though I already learned this then there's the Iframe stuff what do I do then, please! Im begging y'all! ???

I can't see the reason why your code doesn't work, unless you have it linked wrong. It would be helpful to see your page code and full css (that is if you have more than posted here).
What exactly do you want to do with iframe?

Asking nicely would get you help aswell, no need to beg ;)