If you want the repo to live in the base directory of the parent repo, just run
git submodule add https://github.com/scottc11/ok-drivers.git
Otherwise, specifiy a directory
git submodule add https://github.com/scottc11/ok-drivers.git <path-to-directory>/ok-drivers
First, cd
into the submodule directory and checkout a new branch with git checkout -b myBranchName
You can now commit changes and push to the remote
Use the doxygen syntax for adding method descriptions etc.