UPDATE: 

Sorry if my question seems slightly "beginner" as I'm one.

So I created an app on salesforce. Of course I populated my objects with data to see if what I developed worked the way I wanted to. 

Now I would like people in my company to be able to use that app. 

How do we do that?

Create a user? Done
Create a permission set for that app and assign it to that user? Done

Question 1> Is it normal that when I log in with this newly created user, I can't see any of the data I've inputted as a developer?
Question 2> We are a small cie (need 3 users), and we only need that app that I've created (noe of the other CRM stuff), what license do you thing we should buy? platform?

Thanks for your advices.

**WHY can't I check any of the boxes in Custom Object Permissions in my user profile edit?**