apologies in advance

Hi, everyone. I checked all of the memories regarding my question and I'm still having a very hard time with it. Whenever I upload any graphics that I make in Photoshop CS, they look awful - the coloring is off and everything is fuzzy. I've done the whole "Save for web" bit and saved it as a .png at maximum quality and it still looks bad. Am I missing something? Thanks in advance, everyone!

P.S. All the tutorials in this community have been awesome so far. (I just joined a few days ago.) I'm learning sooo much. :)