Im new and i cant find out how to mix up some songs on the site without uploading or anything. Im not sure you even can. If you can will someone please explain how. That would be great. Thanks

Yes you can mix music from this site.

yes, you can :-)

step 1: download some stuff you want to remix
step 2: remix it on your computer using the software of your choice
step 3: upload your remix, giving credit to the parts you have used in your remix (there’s an easy to use place for doing that on the remix upload page).