Tweetdeck groups are now obsolete. They have since been replaced by Twitter lists, which are the universally accepted way for organizing contacts.
Some of us who started Tweetdeck groups previously, don’t want to recreate them all over again in a tedious fashion. Thankfully, Tweetdeck has an easier way of exporting these contacts, though it may seem a tad daunting. Here’s a graphical step-by-step on how to do it.
1. Click on the Group name. You will be shown two buttons. Click on “Export Group As List”
2. Name the list (Oh, I found out you cannot start the name with a non-letter). Describe it, if you want, then select whether it’s going to be Private or Public. Then, hit the “Add list members” button
3. By default, all the members in the Tweetdeck group are listed on the right already, but Tweetdeck allows you to add even more from your general list. When done, click “Save List” and wait…
4. Wait… wait… waittttt… When it’s done, your new Twitter list will have been created. You can delete the Tweetdeck group now, if you wish.