Mk4 parts missing, noob helps required please

[lew145]

Hello, Ive been playing ksp over a month now and have give up on the new campaign as i'm finding the money a bit hard for a noob player, so i'm using science and sadnbox to test different designs and to get better at flying and figures out how different parts work properly. ive started using mods and in my own personal quest want to make my won versions of the thunderbirds from scratch, i have tried installing the mk4 mod to make tb2 but i don't seem to be getting any fuel or cargo options for the craft only the engines the cockpits and the service hatch. i have done my best to follow guides about putting in the game data folder but nothing seems to happen, can anyone helps a noob out as i'm struggling to get it to all appear in sandbox mode.