Firstly, by running the command:
$ ls -la
You will get a list of all files and folders in the current directory you are in. If you want to grant rights to a certain user, just run
$ sudo chown -R username:usergroup directoryname
To give rights to all files and folders of the current directory to the user marc123 of the user group "developer", run:
$ sudo chown -R marc123:developer .