Rounding corners?

[Ananaias]

Is there a way to round my corners so they look less... glitchy?

http://puu.sh/zegu

That's a screenshot of how my corners look at the moment. Outside corners look like that, inside corners look fine. What can I do to fix it?

Sorry if this is an easy fix, I just started this stuff about an hour ago ;~;

EDIT: Haha, I just found it