Adding a contact to the shortlist can be done on the Contacts grid page, the Advanced Search, the Contact's record page and from a shortlist.
From contact record page
Click the 'Add to shortlist' button on top of the contact record page to choose a shortlist to add the candidate to. From this screen it's also possible to create a new shortlist to add the contact to. Color and status are optional.
From Contacts grid
When viewing the Contacts grid (Leads, Candidates, Clients or All contacts), you have to ability to select one or multiple contacts to add to a shortlist. Use the checkbox on the left of each contact to mark them to be added. Once done selecting, open the mass action drop down menu, select 'Shortlist' and click the 'Go' button. This will open the above window to either select an existing shortlist or create a new one for these contacts to be added to.
The color and status are optional.
From Advanced Search
Adding to shortlist from the Advanced Search works the same way as adding from the contacts grid, select the relevant contacts using the checkboxes on the right side of the screen for each contact, choose the 'Shortlist' option in the mass action drop down menu on the top right and click 'Go'.
On the shortlist page, on the top left, you'll find the 'Add contact to shortlist button'. Clicking this button will open a button allowing you to select an existing contact to add to the shortlist, or using the 'Create new contact', create a new contact record and automatically add it to the shortlist. The modal allows you to select a color and status for the existing contact to be added to be added to the shortlist.