FIrst of all, I am not a lawyer. Any advice I give is not a official legal advice.
If you are exploring copyright, you really should invest some time learning about it. Read about its history, what it is and what is is not. Maybe try to talk to an “IP” lawyer about copyright in general and your situation in particular.
You can often adopt a pre-written license (or license template) instead of drafting a license from scratch. Since your intended use sounds rather like “open source”, you could check The Open Source Initiative license list for a reusable license that fits your needs. For instance, you might like the MIT License or the Artistic License, but you should really try to review as many of them as possible (including ones not in the OSI list) before you decide to use one.