Can someone show me how to make a customizable house?

Baisically, im trying to make a town and city game where you can buy a house, edit it, work at a job, earn money etc. But i have no idea how to.

I'd start with the basics. This is quite an ambitious feat, and there's no way to do it. I'd learn some Lua, then work up to making something like that. ROBLOX Wiki is a great place to learn, they have a ton of tutorials.