Hi djsergio, welcome to the forums.
I am sorry for telling you this but you wont find such tutorial around here. Actually, what you are asking its complex and time consuming and it demands for a considerable experience on game development.
However, you can take a look at this
thread about that matter.
If you are new to 3dgs, my advice to you is to go through the resources and link pages, tutorials, workshops, etc., there are many resources on this site.
Hope it helps.
Um abraço!
