Default [Q] How to use external sources to build for a specific device

Hi xda!
First, my device is Wiko Darkfull(not officially, or unnoficially supported by cm)
Second, wiko provided me the entire source code, and i'm not familiariezed with the git and the build process.
But i've like to know, how to in the build process, to "point" to the git, the location of the sources(external).
In the source folder(wiko darkfull source folder), there is all the files needed.
But how i make git build from the external sources?
And, could someone, tell me everything, but with a little guide , i'm kind of noob
Thanks for everything.
Davidosky99

PS(My english is not the best...i know! )