EXPI, I would first start with opening your driver's door to get the overhead light on. Now, with the door still open, does the light dim slightly, remain at its normal brightness or go completely out? If the light remains at full brightness, your starter is not getting any power. If it goes out completely, you have a power issue most likely. If it dims, you should be hearing the starter click.
With this being said, open the hood of your truck and connect a multimeter across the battery. You should get 12.6 VDC with the truck off. Now, position the multimeter so you can see it as the truck is attempted to be started (use of a second person may be handy). Did the voltage drop to less than 11.0? If yes, then you have a bad battery, get a new battery and start over. If it remained at 12.6 VDC, then you are not getting power to your starter. If it went to 11.0 to 12.0, then your starter is getting power, but something is restricting the current (bad cables or bad starter solenoid).
If you are suspecting a bad starter solenoid or starter, try this: remove the cover just to the right of the battery to expose the starter solenoid (not the piece on the starter, that is only a coil to engage the lever to engage a gear). If you look you will see 2 large posts and a smaller post below. Take a large screw driver or similar piece and touch both of the large posts at the same time (this should case a decent amount of sparks, so, don't be too shocked). If the motor turns over in this case, then you have either a bad starter solenoid or the control circuit to the starter solenoid is toast. You can repeat this check by going to the large post nearest the battery and to the small post. If the motor turns over now, your problem lies in the dash (either ignition switch, PATS module, or associated wiring). If the truck doesn't turn over going to the small post, then your starter solenoid is toast. Replace.
If when you shorted the two large posts together you got very little spark (or no spark at all), then your problem lies in the cable going to the starter or the starter itself. The easiest check is to hold a multimeter to the large post on the starter as someone else tries to crank the engine over. If you are getting over 10 VDC, the starter is toast. If you are getting under 10 VDC, the cable is bad.
This should get you fixed up. IF you have further questions, just ask.
