Has anyone seen this movie and will they please explain it to me?

This is a still from the film "Primer." It's a really awesome movie.

I just have no idea what happened in it. The movie is less than 80 minutes long so I really should just go watch it again. I even went to the wikipedia page about its plot (SPOILERZ ALERT!!!1!!1!), read it, and I still don't think I get it.

It's basically about these two guys who accidentally invent a time machine. Sort of. But it's not like a usual time machine that can jump you back and forth across time willy-nilly. I'm not going to try to explain it because a) it will ruin the movie if you want to see it an b) like I said, I don't think I understood it.

Please, if you understood it, email me a comprehensive summary.

I know. This wasn't a funny post. I legitimately need help understanding what I think was an awesome movie but I'm not sure. I need my opinions given to me, you see.