im trying to uplaod some mp3s on my pc to the web so i can play them on my xanga site, is there any way to do it? just put the file on a random url on web to be used from? if so, how do i do it

Well, for a start, only posting the question once usually helps
You cannot just choose a random URL, the only way you can put files on the web is if you own the space where those files are stored.
There are plenty of websites out there that offer "free" storage - take a look here for a list of free webspace providers. Note that I haven't actually looked at any of these sites, so I can't guarantee their reliability or quality, but it's a good starting point.
Once you have your online webspace sorted out, you should just be able to upload the files using an FTP program, such as CuteFTP

If you want a free FTP client then look at Filezilla.