* 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
* 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
To enable sorting on a has_many relationship set up an interger field on your data object. Also for has_many relationships make sure to set the $default_sort on the dataobject to this new interger field to ensure that the sort order is applied when the relationship is requested. For many_many relationships you must add a $many_many_extraFields static to the data object defining the relationship, see the SilverStripe documentation for more information on this. If you are using a many_many relationship you will need to do a custom getter to set the sort order of this relationship for use on the front end see bellow for an example.