How do I modify my IP adress?

I’m obviously not an expert in the field.
I’d like to know if there’s a way to edit IP adresses so to be ‘protected’ whilst connecting to the web via a PUBLIC / PRIVATE but unprotected WiFi.
Appearantly I’ve just got a signal ( quite strong it seems) and was tapped in to it automatically.
I assume it is a private WiFi ( as in individual and not belonging to a company ) . Possibly a network here in the neighbourhood.