ok i just used magnetic lasso tool to select that render that was already cut...ya and it like blended the sides already for me and it looks like it would be on soft light on a sig(like its see thru) but its on normal...please help
1. Why would you use the magnetic lasso tool to select it? 2. You probably pressed delete while it was selected, which made it blurry on the edges.
Um, most people save renders as .png, so all you do is right click the render, click save as, save it somewhere, then go into photoshop then do File>Open, then open the file you saved. It should automatically be transparent in the parts cut out.
if its already rendered you can just use the magic wand then select the inverse with ctrl + shift + i then cut it out and paste it to what you are working on