I hope this helps y'all! just watch, and there are a few things you left out, so i'm just going to tell you now. once you get to your project, go to the SOUND tab, and put it in there, and once you have put it in there, just go to the sound blocks, and if it says, play sound, and the song you got from some other scratchers project, you should be good, if it says play sound "pop" then click the arrow on the block, or delete the "pop" sound. don't forget to give credit!
Credits to Frost Bite The Rouge for teaching me how to do this my self!