Everybody has things they're good at. For some, it could be creative pursuits like drawing, writing, making music, etc. For others, it can be more strictly social pursuits, like what the others have suggested—getting to know people, expressing yourself, participating in discussions, etc. It could be making people laugh, or helping them feel better, or simply being a listening ear when they need somebody. Or heck, it could be as simple as talking to other furs here about your days, or uploading pictures, or keeping a journal in the journals thread.
The point is that contributing to this community is much easier than you may think, just as everyone else here seems to have said.