Add Carriers in group from All jobs

Check related article about how to offer a job to a carrier group -                                                                 Send a job offer to a group of carriers

In All jobs check the box near carrier(s) you want to add into groups. (Job should be dispatched)
Select Assign to Groups

Select the group you want to add or type a new one

Click assign:

IMPORTANT!

If you create a new group, use the ESC button or click outside to close the groups list.