Hi,
If you do not have a static IP (constant never changing IP) then you will need to sign up for a DDNS service. These services give you a constant web address (URL), that works along with your router to make sure you always reach your router when you type in your web address. There are many different DDNS services, I would recommend seeing which one your internet modem recommends using as most have a default choice that they are setup to use and only require you to enter the user name and password.
Regards,
AltoEdge