* Download the module from here https://github.com/UndefinedOffset/SortableGridField/downloads
* Extract the downloaded archive into your site root so that the destination folder is called SortableGridField, opening the extracted folder should contain _config.php in the root along with other files/folders
* Run dev/build?flush=all to re-gernate the manifest
* Upon entering the cms and using GridFieldSortableRows component for the first time you make need to add ?flush=all to the end of the address to force the templates to regenerate