I have and was awarded Post-9/11 GI Bill education benefits.
Since you were awarded Post-9/11 GI Bill education benefits you GI Bill Statement of Benefits will show you how much of your benefits you've used and how much you have left to use. I suggest you view  your GI Bill Statement of Benefits.
Is there a way that I can apply for benefits online?
Yes you can use the GI Bill Comparison Tool to apply for education benefits.