When using Redtail's Seminar Management tool, one of the steps you'll be taking is to add contacts to your seminars. While you can add contacts and their guests one at a time from within the tool itself, you also have the ability to add contacts to a seminar in bulk from your Advanced Search page.
After running an Advanced Search that will include the contacts you want to add to your Seminar, you can then select the names that you'd like to add.
Then, click the Contact Options menu to the right of your search results and select Bulk Actions:
Next, select Add to Seminar from the Bulk Contact Actions modal that appears.
You'll then see the resulting modal:
You can then choose from your existing Active Seminars in the Active Seminars box and from available seminar statuses in the Attendee Status box.
Then just click add to seminar. Those contacts you selected will now be listed as Attendees for the Seminar you selected and be listed with the Status you chose here.
Note: you can delete contacts from an individual Seminar in bulk as well. From the Manage Attendees page for the Seminar, select the attendees you'd like to remove, click the "Attendee Options" button above the list of attendees, and click "Remove Attendees."