what about making it more interesting so people sign up and join, what would you suggest then?
I see some of these users posted "nice one", "I like it". They aren't designers.
You do have lots of change from me as 4+ years experienced designer.
Light blue & yellow are poor colour choice.
"MyBB" header, the stroke is not smooth, can see few pixels there.
Green, black, grey & yellow are not nice colour schemes.
"update: i have darkened the blue gradients, better or worse?"
You have blue gradient mix with grey, its too dark. Worse.
Your forum is not attrative users to sign up. You've got to have colours match like blue, light grey and navy. Dark red, gold & coffee. I'm sure there is online colour scheme tool, which will help you to select correct colours. Search it in google if you'd like.
Final conclusion: I suggest you start again or hire a skin designer. If you want to do yourself. Do first sketch, write a list, pick colours then design your forum skin.
By the way, the icons with navigation links are nice there.
Keep up good work. Sorry if I'm being harsh, I have right to critique in this WebSite Reviews.