My taxes keep getting rejected. They give me the reason, but I don’t see how to go through and amend the error.

We cannot help if you do not tell us the reason.  We cannot see your screen or your tax return.

I know what I need to do to fix it, I just can’t figure out how to actually go back into my taxes and edit what I’ve put.

Have you tried going to the "Forms"  (top left hand corner) ?   It shows a form and the field where an entry may be lacking.  (the required entry may be irrelevant sometime and you can just enter a "0" and move on)

Please provide the rejection code if you are still in need of further assistance. @stickyteeth