Thats like a whole forum post on itself, i actualy did an in depth paper on this for humanities project. Thing was like 20 pages by the time i was done. But ill give you the basics. Use desalination plants to solve the clean water issues. Alot of the land is africa and the middle east is relativley un used to we can use that for food production onve we get the water issue solved. While all this is happening we are gonna need power and lits of it. If we covered the roofs of everyhome on earth we would have almost enough energy to power everything on the planet without gas. Supplement the rest with the other alternative energy sources already in use and build more to fill in the rest. The next big thing is payaing for all of this, they key to this is not to pay for it at all, with all the food, water, and electric needs met people wont need to worry about money if them and their children and all of their childrens needs are met. Next is living space, skyscrapers could serve for basic housing, we would also have acess to extra terrestrial bodies for living space as with all humanity united the treaties in place governing non earth bodies would be nul and void, leaving places like the moon mars, etc.. open for colonization once the technologies become available(which is actualy coming very fast at thw rate of todays development. Anyway got to go, like 6 minutes into my class right now and still typing XD more later.