To import your list, click Subscribers. Now you can either add the subscribers to an already created group by clicking the green icon. Or, when you're already inside a group, click Add new subscribers. In both cases, it will bring you to the same screen.
There are 3 methods to import subscribers:
Afterward, press Import subscribers. Then you should see a small preview of the specific columns. You can assign data fields for columns too.
If you don’t want to upload data from a specific column, leave it on Skip this column. When you’re done, click Finish adding subscribers.
After importing subscribers, you’ll see exactly how many have been added to a specific group, how many there are in total and which subscribers have been updated.
In this video, the uploaded 899 subscribers already existed in another group. This time I also uploaded a name column, so now the names have been added too (this update counts for all the groups they subscribers are in).
You can also see what subscribers haven't been added. This usually happens when there is a formatting problem in the email, and you can fix this by editing the email and then save the subscriber again.