Al Dairi

When attaching two pics (i dont neccessarilly mean two layers). I mean connect them where one in the right and one on rhe left. Assume each represents a photo for the sky. Now around the middle line where the two pics meet, they dont have same level of blue color. So anybody can figure out they r 2 pics not 1. How can i avoid this and make the color lvl change gradually?

When you try to select a human face (and maybe body) from a complicated background then seperate it. You'd end up with this face having small parts comming off its edges (ends). You might try to use the eraser to some extent. Still the face or body will not look smooth. How to smoothen it?