If you’re completely new to FontCreator, start by browsing through the help file.
I always find it helps to go through the menus and dialogues to see what I can learn before even opening help.
I don’t have time to write again what was written in the thread that I linked to before.
There are several issues that must be decided before starting the design process. You didn’t answer my previous questions, so I cannot advise on the best route.