Once you have generated a list of Prospects select the box each Prospect your wish to convert into a contact. If you wish to select every Prospect result on the current page you are viewing, check 'Select All.
When you're ready, click Create Contact. Be mindful of the number of credits left on your account, creating 1 contact costs 1 credit.
All set! Find your newly created contacts on your Contacts page or off your Gmail Contacts sidebar tab.