If you are on fiber, sonic only allows dynamic ip, otherwise, sonic allows you to choose a static ip.
If you have dynamic ip, you can use a service like dyndns or no-ip to be able to resolve your home ip from outside your home.
you will need to setup redirections for specific ports on the router to your server. for example if you want to run an http server, you will need to forward tcp traffic on port 80 to the local ip f your server. You will also have to ensure your server always uses the same local ip. There should be a reservation table in the router webUI to set a static mapping between MAC addresses and IP addresses.
All these settings are accessible thought the webUI of the router and access information (url, password) should be on a sticker on the router.
Ensure your passwords are not default!
If you are not sure what you are doing, maybe you should not do it.