How to use a grease gun
What is it?
Parts of your car need greasing, and this is the tool you use to inject grease in to difficult areas, usually through 'grease nipples,' for example every few thousand miles / years it's worth greasing the front axle on an old VW.
Once you can see how it comes apart and loads, you won't need much more help using a grease gun, so read on for the simple procedure...
How to use it
To load a grease gun with grease, first unscrew the barrel from the handle/trigger unit. The barrel is where the grease goes and you've got two options. If you've got a new tub of grease with a large plastic washer in like I have below then you can load the grease directly in to the gun from the tub. Otherwise you're going to have to load the grease in gradually by using something like a spoon. If you do use a spoon, don't use the one you're going to eat pudding with later.
Here you can see I've got the barrel off the gun and I'm getting it lined up with the opening in the middle of the 'washer' in the tub of grease. You can't see the plunger at the end of the barrel as my hand is over it, but it's a long way in to the barrel.
Once you've got the opening in the barrel over the opening in the tub of grease, push down on the barrel and pull up on the plunger at the same time. If you've got a tab that keeps the plunger still, you might need to press it / fiddle with it to get it to release so you can pull the plunger up. As you push down / pull up the grease is pulled in to the gun. When the gun is full or tub of grease is empty, move the barrel sideways to cut off the pillar of grease you've made inside the barrel, then clean off the end of the barrel with a bit of cardboard / rag before screwing it back in to the handle/injector unit.
Below I'm pushing the barrel in to the tub of grease and pulling up on the plunger, which isn't very obvious due to the angle:
Once the grease gun is back together, you just need to pump the handle to get grease coming out of the injector end. Sometimes you might need to fiddle with the tab that holds the plunger from pushing back in or give the end of the injector a push to allow the pumping to happen smoothly.