I could do with a little bit of insight please if possible.

Hello,
Really a short question to be honest.
I am wanting to build a modular game similar to crossout but with a lot more to it such as walking around in First person/Third person where someone can get a part and place it on a vehicle or building …etc. I am just wondering if there are any tutorials out there that could help me in the right direction as to how to make a game that people can build stuff in with object i add into the game such as vehicle parts, building parts and other objects i will be adding in. I am after a tutorial if possible or maybe even some more help if there is anyone offering it.
Many thanks in advance.