Generally Electric has a three part guide to taking a guitar idea you come up with and transferring it into a simple demo that you record on your computer. These directions have specifics about using Apple's Garage Band software but there are some larger principles that can be applied to anyone using a computer to record guitar.

Part 1: The Basics of Recording
Part 2: Creating Loops/Backing Tracks
Part 3: Effects and Finishing Up


An excerpt:

"Going through this process will have introduced you to the basics of recording. There’s a wealth of things to learn about recording, but remember that the music itself is the most important thing, and what we’ve covered here is all about demonstrating your musical ideas.

I find the following points useful to keep in mind:

Keep it simple: don't go overboard with multiple parts and special effects. Think of this as the musical equivalent of a sketch on the back of a napkin: just put down what you need to communicate your idea.

Get it down: don't spend too long tweaking. Get a basic beat down and record your parts over it. You can always expand and improve it later, but don't let your inspiration fade while you're programming a tambourine part.

Come back to it: when you're done, leave it alone and do something else for a while. Come back to it later with fresh ears and see how it sounds.

Don't compare: don't worry that your demo doesn't sound like a professional recording, because it's not supposed to. Remember that it's only meant to communicate an idea, and many of your favourite songs will have started life in the same way.

Experiment: if you don't know what something does, use it. The more you play around with this stuff, the more you'll learn and the better your recordings will be."