one day some one will reply

please I really need to know how to enter a creative/dev mode to make stuff

You enter dev mode from the options menu (4th option iirc) UNLESS you permanentely disabled itone day when you were young and foolish.
Now you've got a bunch of little white icons on top of your screen, but you're really ever only gonna use three of them.
The little head is the god mode toggle. In god mode you have access to all buildings regardless of research, also building is free and instant. So is deconstruction. And when you select stuff you're gonna see a bunch of big pink squares alongside your usual gizmos, these are stuff like set fuel to full/empty, complete hack, etc for when you need to try out stuff repeatedly.
On the right of god mode's icon is the dev palette. Its empty for now; but turn it on anyway. Thats where we're gonna store our shortcuts.
Now for the main dish, fourth button from the left, debug actions menu. This is where the magic happens. I'll let you explore on your awn; most stuff is pretty staight forward. See the little pin at the end of each button? Thats how you stick that particular button to the palette, so you don't have to come back to the menu everytime you use it. Here are a few you can pin right away : set terrain, edit roof, clear area, clear all fog; T:Kill, T:Destroy, Spawn thing, Spawn thing full stack, quickspawn.
There you go, have a nice day!