If you honestly truly wish to create a project you can be proud of, you should be ready to invest a year to see it to completion. The modding comes quick, the learning goes long.
To start off, download the HEK and make a custom level. Custom Maps are actually the easiest thing to make, compared to custom weapons or vehicles.
Once you have a custom map, many many people have already released weapons and vehicles that you can download and add to your mods.
The most important thing about this is that you learn what you're doing. Shortcuts to get to a finished product never
help you, ever, in any part of life. The end result is nowhere near important as being able to replicate it.
So when you need help post here and ask. To get started;
- Download This
- Acquire 3DS Max. (Don't ask how to get it, we don't discuss piracy on forum.)
- Watch These Videos. I learned CE from the very same ones.