The vast majority of popular chord progressions on the guitar are played in keys that are predominantly open chords. These would be the key of C major and G major, (maybe D major).
We will be using the key of G major in this module (G Am Bm C D Em F#dim).
Most progressions will start on the I chord (which is often a big clue to identifying what key you are playing in). We will do the same and add to it the IV chord (C).
A I-IV progression (G-C) is a very useful two-chord progression to use as a backing for working on your lead playing. At this stage that would be learning your major scales and trying to use them to create melodies, both in single note lines and harmonised thirds.