Currently building first PC and am stuck. plz help

Just got the rest of my parts in the mail today and started putting it together. I am currently trying to do a external build to test the parts and having trouble putting on the stock fan. Sounds dumb i know but the clamps dont align evenly on the sides. What am i doing wrong plz help.

This is the how to build a pc from teksyndicate. There's a damn push pins section for you to skip to. Should fix your problem.