Heh, well, that's certainly a good enough setup to start with.
The progression of learning is, I think, ultimately different for everyone. There isn't really a set science to it, only what comes naturally to you and seems to benefit you the most. If starting with learning basic chords and playing parts of songs is actually useful to you, then by all means just keep at it. There's nothing wrong with that method at all, and you'll eventually try to learn new chords as you try to play new songs that have stuff you aren't familiar with how to play yet. If writing your own stuff helps you, try just coming up with basic chord patterns you like and write some basic lyrics to go with them. That can be fun because it gives you something to occupy your mind with, to exercise your creative side. So you're learning how to do stuff, or maybe after playing a few basic chords together you realize something else would sound good, but you don't know how to play that chord... so again, you stretch yourself beyond what you currently know to learn. In either case, chords will eventually start to bore the hell out of you and you'll start naturally experimenting with picking techniques, with playing different note patterns, with trying to get different sounds out of the strings by doing different things to them.
But really, I suggest you try to learn piano. No, I'm serious. I mean, not really, but kind of. I learned how to play piano for several years before guitar, and it gives you proper perspective on what the guitar is compared to everything else. Have someone who knows how to play piano sit down and try to teach you a few things, or get a little self-teaching book and sit down at your grandma's piano or something sometime. Hell, just sit down at a keyboard and spend 45 minutes trying to make sounds that don't sound horrible. The biggest motivator you'll ever have is realizing how utterly, ridiculously easy it is to make a guitar sound decent, even when you have no fucking idea what you're doing, compared to basically every other instrument on the planet. If you try to learn piano, you will sound like absolute shit for months upon months. Guitar? Teach somebody 3 chords, and they can make noises that aren't unpleasant to the ears. Then when you realize they can simply hold down a single chord and pick random individual strings to get different notes that all sound good together when played in different patterns, you'll realize what a miracle the instrument is.
