Bazzi is correct!

Assuming you have a bad starter in right now, it goes like this:

1. Disconnect the Negative battery wire (VERY IMPORTANT)
2. Locate the starter on the passenger side of the truck attached to the bellhousing of the transmission
3. Disconnect all wires that go to the starter (You did disconnect the neg batt. terminal, didn't you?)
4. Unbolt the bolts that hold the starter to the bellhousing
5. Carefully slide the starter out of the truck however you can, be careful not to drop it on yourself
6. Smile and be proud of yourself

7. Pick up new starter in hand
8. Slide the new starter back to the bellhousing following the same route used to remove the old starter, but in reverse (don't drop this starter on yourself either, it will hurt just as bad as the old one)
9. Bolt the starter back up to the bellhousing using the correct bolts in the correct positions
10. Hook all wiring back up to the new starter
11. make sure all tools are out of the engine bay and not left in there
12. Reconnect the negative battery cable
13. Test to see if it will start your truck
14. If it does, you did dun a good job!
15. If it does not start, either the starter is not the problem, or you did something wrong.

Good luck!