This page documents the dialog that is displayed when you click on the "Grant Access" button at the bottom of the Edit Individual page.
You are presented with a list of all of the other users registered on the family tree. You may filter this list by entering a value in the pattern field. When you leave that field the list of users is updated to include only those users whose name includes the value.
Select one entry on this list of users and then click on the "Grant Access" button. That individual is then granted authority to update the selected individual, all of that individual's ancestors, and all of that individual's descendants currently in the family tree. Note that if you subsequently add ancestors or descendants the grant does not apply to them proactively. When you add an individual you are the only owner of that individual until you grant access to someone else.
The response displayed to you when you click on the "Grant Access" button is a page listing all of the individuals for whom the access grant applies. The listing identifies the relationship between each person and the base individual, the internal unique numeric key of the person in the database, and the name of the person. For reference purposes you might want to print a copy of this report or save a copy as a file, so you can keep track of to whom you have granted access to members of your family tree.