Minecraft Single-player world?

Okay, so me and my friend have been wondering how you can connect and like play together on a single player world. If anyone could tell me step my step a way to let me and friends to connect that would be great, thank you

Normally Single Player worlds are just that, Single player(like just you.), and for you and friends to play together in Minecraft is to make a Multiplayer Server World.

Although a while back Mojang added a feature called "Open to LAN", where you can have your friends join you in Single Player worlds. There's a lot of videos on youtube that tell you how to use Minecraft's Open to LAN feature. I should point out your friends can only join you if they're within the LAN(Local Area Network) area you're playing at.