I assume you already know where the filter is located (Inside frame under driver seat). Some fuel lines require a special tool to remove them from the fuel filter, others have a red tab that needs to be pushed down and then you slide the fuel line off. Luckily, I had the ones that didn't require the special tool though that can be purchased from AutoZone etc. Fuel will come out of the lines unless you hit the fuel pump cut off switch and let the truck run until it dies from lack of fuel though, I didn't do that. I disconnected the fuel line going to the engine first and had a bucket ready to catch any fuel that came out. I would guess about a half cup to a cup of gas game out. Then I removed the other 2 fuel lines and took the filter off and put it in the bucket and put the new one on. Connected the fuel lines, cleaned up any gas that spilled on the frame, and then started her up.
Some people say that gas will spray all over the place but mine didn't. Pretty easy thing to change out. Just be careful with the lines, mine were plastic and if one of them broke, I have no idea how much it would cost to replace them (I wouldn't think they are cheap) so take your time. I suggest you wear safety goggles when doing this job and not lay directly underneath the fuel filter when you disconnect the lines (No need to get gas sprayed on you and in your eyes). Hope this helps some.