To do this, click on the 'Dashboard' button for the folder of your choice in your practice area.
Then all you have to do is send an invitation to the email address you have chosen from the "My users" tab.
For each guest user, you can grant more or less extensive permissions by assigning them to specific user groups. For example, if you want your guest to have the same permissions as you, assign them to the "Administrator" group.
The guest will then receive an e-mail invitation to register with Okimia.
NB: you can modify the rights and permissions granted to each group by clicking on "Modify my groups", then ticking/unticking the boxes according to your preferences.