Definition of purvey. purveyed. ; purveying. transitive verb. 1 : to supply (as provisions) usually as a matter of business. 2 : peddle 2.
Using a capo is easy. You just have to think of it as a movable nut. Clamp it on the fret you will use for the key you are playing in, and just play chords or picking from a key you know. You can play in G using chords from the key of F if you put the capo on the second fret.
You can also use a capo to transpose the key of the song. A capo is a device that instantly changes a guitar's key by clamping down all the strings in a particular fret simultaneously, in effect creating a new nut. While it's always a good idea to have a capo on hand, it's an even better idea to know how to transpose keys in your head. After all, the more skills you have at your disposal, the more versatile a player you'll be. For more in-depth instruction on how chords work, check out Introduction to Music Theory.