Same here. I wouldn't suggest building your first. Yes, they're easy to build, but you really need a working knowledge of all the parts, what they're called, and most importantly WHY you want a particular part. Just because it's popular doesn't mean it's going to suit YOUR purposes and expectations. I would strongly suggest an M4-type carbine for your first. Get that, then you can pick out an optic and other accessories like a weapon light, and customize it if you wish.
There are several good guns out there right now for reasonable prices, and that will wind-up confusing you, too. However, for your first, theres no reason to spend over $800-$900. Take any extra you may have and buy mags and ammo.
To make it as simple for you as you can, I would simply buy a Spikes M4 LE. High quality, no corners cut, has all the features that you'll neeed for a trouble-free, long-lasting rifle, and you won't need to upgrade anything. Down the road, you can add things you may find you want (rail, different stock, etc.) but the basic package is already there.
If you were to go through a catalog and pick the parts you'd want on a rifle, the Spikes comes with 90% of them already. BTW, I HAVE a Spikes, and have built several up using all the major Spikes components. IMHO, you simply can't go wrong.