Well, looks like you found this site helpful enough to pay for the membership. As you've found out there are many people here who know a lot about these trucks and their inner workings. Welcome aboard!
You could not have picked an easier vehicle to learn on. I can't think of anything on these trucks that is hard to diagnose or difficult to repair.
A 5/8ths spark plug socket (very common), a short extension, and a ratchet is all you need to remove/install a set of spark plugs. You'll want a set of feeler guages or spark plug gap tool to set the spark plug gap correctly. Usually when you buy them new they are close, but I check them before install.
Since you are new to this, replace one plug at a time. You can remove a plug and set it down on a piece of paper (or just line them up) in the order they came out of the engine if you want to compare all of them cylinder by cylinder. Ideally, you want dry and lightly toasted coloring on the plug. No black soot, no fuzzy ash, no oily wetness. It is normal to see some wear on the plug terminal (basically a rounded edge on the plug terminal). All of the plugs should be similar in color. Any major color differential from cyl to cyl could mean there is a problem.
Some things to note, and your manual should have this info too.
firing order, 18436572
the distributor turns clockwise
drivers side of the engine is odd numbers 1357 with 1 towards the front
pass side is even numbers 2468, obviously 2 is towards the front
Keep in mind also, general tech Qs like this will get a better response in "The Garage" section of the forum. I don't know why, it's just a higher traffic area. And I shouldn't say "better", what I mean is faster and more abundant.
