Watch some videos on how to port forward for your specific router.
Couple of things you'll need:
IPV4 address of the computer you are hosting your Minecraft server on
Your public ip address, which can be found by google searching 'what is my ip'
Forward port 25565 (or whatever you're using for Minecraft) to the IPV4 address of the computer you are hosting the server on.
If you want to connect to your own server, you'll need to connect to the IPV4 address + Port. (Example 192.168.1.100:25565)
If you want your friends who aren't in the same home to connect to the server, you'll want them to connect to the Public IP address of your home + Port. (Example 58.29.22.95:25565)