What do I need to use my home wi-fi for my devices away from home?

While I'm not completely bewildered by technology, the amount that's out there and the new stuff all the time can be overwhelming. When I ask friends this question, I get a broad reply and am too embarrassed by my lack of tech knowledge to ask them to clarify.

I have a password-protected home wi-fi. When I'm home, my iPhone 6 automatically uses it. However, when I'm away from home (even at my best friend's next door), of course I can't reach my wi-fi.

My iPhone is the only device I'm interested in using with my wi-fi outside of home. It is not jailbroken, nor will it be in future. What, exactly, do I need to get or download (if there's an app) in order to hook it up to my home wi-fi when I'm not there? And if it is some tech item rather than an app, what type of store would sell and what precisely do I ask for? Go ahead and give me the Tech for Dummies version of an answer. :) I don't have much money, so I want to get it right the first time.

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