You can add new users to your Synap portal in a number of ways. To add new users as an admin, go to the Users page, and click into the appropriate user group you want to invite people to.
If you already have people in your group, the screen will look a little bit different, the Add Users button being in the top right hand corner:
Click 'Add Users' and you will be presented with a pop-up window. This will let you either add existing users to the group (i.e. if they are already registered on Synap), OR you can invite new users by entering an email address. New users will receive an email with instructions on how to sign up.
If you have a newly set-up portal, you will most likely be looking to invite new users. This screen will let you enter a comma separated list of emails, or you can upload a CSV file (1 column). You can also enter a custom message to personalise the emails that are sent out.
You can view the status of invites you have sent out by visiting Settings -> Invites: