Index is the hunt group number - just a placeholder
Callno is the number you dial (or forward to) to reach the hunt group from internally.
DID is an outside number you can dial to get directly into the hunt group (if you have DID service and hardware).
Name is the name of the hunt group - may show up in displays.
Type is the type of hunt group - linear (always starts at the beginning and goes thru all phones in order) or circular (starts with phone after the last one that rang first and goes thru the list, then starts over at the beginning and keeps going).
Ring type (1,2,3) is the way a call from that hunt group will ring on the phones. 1 is normally the same way everything else rings, and 2/3 can be some combination of short/long rings or triple beeps or some such - play with it. This is how you can tell a call to the hunt (or UCD) group from a regular old phone call.
Tel. Directory determines whether the hunt group number shows up in the system phone directory. I've never used this, so beats me what it does.
After you set up your group parameters you can then drag and drop the extensions you want in the group from the Selection box to the Members box and set the order they ring in the group (by the extension's position in the list).
Hope this helps.