I'll be honest, if i came across this site over google or something i would never register. I'll give you some feedback which maybe you can use to improve your site.
Logo: The logo is a bit to simple in my opinion, it needs a bit of spicing up. If it were me i would increase the size of the banner and add a nice big banner with a logo and maybe a little bit of text saying what the site is, like mine for example:
www.cssfeeds.net
Overall Theme: I've had MyBB before and i used the red version of this theme. The theme is nice but it lacks any uniqueness, the only thing thats changed is the logo. I think you should decrease the width of the forum and make it fixed. You should experiment more with the site, make sure you have a backup and do a little editing here and there and try out some different icons e.x.
Layout: Well, its a mess ... there are forums flying all over the place. You need to give it more stucture and i think you need to use the subforums feature more. If you use the subforums feature a little more then you can make your forum look more popular because you can stack the posts and increase the post count for a particular forum.
Statistics: I don't know when your board was started so i can't really say if the stats are good, but 4k posts is nice
🙂
Activity: Activity can always be improved but the activity on your site look fine to me.
I hope you find some of my feedback useful, good luck with your site.