Watch the Identifying the Key online guitar lesson by Matthieu Brandt from Songwriting on Guitar
Here you are; jamming a great groove and a good sounding chord sequence. It's a good thing to step back at some point and evaluate what you have. One of the first things to look at is the key you are playing a chord groove in. Finding the initial key of a song will give you your first melody options. You don't have to stick to those throughout your song. And every chord can have it's own set of notes that sound good. But getting some solid ground beneath our harmony we'll help your ear in finding other chord options and strong melodic movement. We'll first look at major harmony and get the tools to find 'home base'.