2004 Silverardo LS.
My AC is weak on the cooling. I'm not sure if I can try the the "quick recharge" canister route. Is there are process I need to follow - how do I do it?

 

If there's still refrigerant in it, yes, you should be able to charge it, but this means you likely have a leak, so recharging it is a band aid.
The DIY-friendly canisters with the built in hose and port connector are over priced, but if you don't anticipate needing to do AC work often and don't want to invest in a proper manifold gauge set etc, then they will get you going. A very concise instructional video can be seen here:

 

It will probably cost you more in the long run vs having a good a/c shop diagnose & fix properly.