Can you amend your taxes by refiling?

I started my own transportation company last year. I filed my personal taxes already becuz I needed some quick cash. Now I'm having a friend do my business taxes. He said he was going to refile my personal with my business taxes even though I'm LLC and that would amend them; but doesn't sound to sure. It seems like he just trying to rush and get them out the way. Does anyone have a clue what I'm supposed to do? It's kind of late to get someone else to do it.