groups
If you set up the group on your phone, you need register the group on your internet vodafone account.
When youre logged on to vodafone, click on the All@once link and then groups to register.
Then to send a message from web to group click on "send from web" while still in the all@once. Sending a txt from your phone is slightly different so have a read of that link too.
There is an app to draft txts from your pc, think its called textbuddy, someone posted a link here recently but I cant find it now and didnt google too much for it as bit busy so.... You might be able to use that to send to groups but youll still have to do the first bit above.