1. Key signatures;
2. Major Keys;
3. Number of sharps and flats in each key;
4. The Relative Minor.
You should try and familiarise yourself with all of this information but if all you know is a Minor Pentatonic scale, perhaps the best thing to learn is the Relative Minor to each major key. This will enable you to use your Pentatonic Scale over songs in major keys, eg. Use Am Pentatonic over songs in C Major, Em Pentatonic over songs in G Major; Bm over D Major; etc....