Set Up Sharepoint

I have a small restaurant and being a tech person at heart, I would like to use Sharepoint for things such corporate documents/correspondence, vendor invoices, HR (with possibly an internal site for staff, for news, etc). Basically, I would like a virtual filing cabinet that's easy to use for a non techie. We only have 4 paid O365 standard licenses - 3 users would have full access, the 4th would have restricted access.