There are a few good ways to do this:
press alt+f2 or open a new terminal window and type:
"browse to and right click on the folder you would like to modify. Then, select "Properties" from the context menu. You can now select the user or group that you would like to be the "Owner" of the folder as well as the permissions you would like to grant them. Finally, press "Apply Permissions to Enclosed Files" to apply the changes recursively.
Though it seems this does not always work for some operations in a deep folder tree. If it does not work use the appropriate terminal command."
enter the following into the terminal (replacing username and directorypath with your username and the path of the folder you want to modify):
sudo chown -R username directorypath
If you are not shure what your username is, (case sensitive!) see the top of the terminal window, it should be something like:
A simple way to paste the directory path is to pull it into the terminal window