If you created the module with Module Builder and deployed properly, the system should create the appropriate url and you should see the link on your menu. If you want to link the module to other modules and display the subpanel under those modules, you have to create relationships from Studio. More info here: https://docs.suitecrm.com/admin/administration-panel/developer-tools/
If you are trying to create call a external Url, then you will need to modify the files manually:
Check documentation here:
https://docs.suitecrm.com/developer/