How to set up my own minecraft server without hamachi but free?

It's called "port forwarding", google it. Setting it up will change depending on the router you're using, so I can't give you specific instructions, but it's the only way to run your own server for free in ANY game, not just Minecraft, so it's a good skill to have. Basically you have to go into your router settings and change some things around, so make sure you know what you're doing before you attempt it.

Sorry I can't give you more details, but a quick google search should net you all the info you need to get started.

Can I join the server?