Playing a Critical Role gunslinger

Okay so I am very new to the world of macros and such one of my players wants to play a Gunslinger and as its not in the charactermancer or anything what would be the best/easiest way to make this happen for them.

You'll have to do most things manually (I don't know if the Gunslinger is on the Marketplace). Bypass the charactermancer and go to edit the sheet directly. On the Options page of the sheet (the gear icon) there is an option to set a custom class, setting its name, saving throws, and hit dice. You'll have to manually enter the features for the class, as well as the guns themselves under the Attacks section.