I normally hate it when someone replies to a question here with "Why don't you google it?" but, on this occasion, I actually commend that idea to you.
I've just googled 'sharpen blades hedge trimmer' and there are several videos (as well as pages with diagrams, etc) which look as if they might help you. Rather than selecting a link to post here (which might not be the best one for your needs), it seems better to suggest that you take a look for yourself.