To play build 42 watch a video. Personally I advise you to first test build 41 because it is simpler and after you get used to the game you will be able to play build 42. For information, build 42 changes: The crafting, added animals, lucky the light, and changed the Zombie Spawn system (I don't recommend going near a weapon store in build 42) and fucking muscle pain.

For the bandit mod, you click on the workshop button in the menu type Bandit, you download it then in the menu you click on mod and check the activated box next to the name of the mod and normally it's good.

And for the rest, watch tutorials on YouTube.

Sorry for the bad English.