How to make a minecraft LAN?

My boyfriend and I are in the same house. He is on the desktop, I'm on my laptop. We want to play minecraft together. So how do I create a LAN server? He went to open lan, and then I went went to multiplayer and waited to see if it would come up. It didn't. So I did direct connect and typed in my IP with the LAN like this "123.456.7.891:56915" The first portion being the IP on the desktop which he created the lan on, and the last five numbers being the port number that showed when he created it. And it keeps saying "Connection timed out, no further information."

How can we play survival together, on peaceful mode, preferably on LAN?

Added (1). I've done all of that. It doesn't show up on my multiplayer list, and we're on the same network.

Log in to minecraft. Start a single player world. Once it has been generated, press start. Select Open to LAN. There are a few options you can do, but to start it, click Start LAN. He should see it in the multiplayer servers. However, before all of this, make sure that he is on the same network as you, or none of this will work

Hope this helps.

1. Open the single player world.
2. Press "Esc" and click "Open to LAN"
3. Choose preferred settings, then click "Start LAN World"
4. It will (should) automatically show up on your Multiplayer list.