A question about rollover or secondary line

[2CansAndString]

Hello I have a question about creating a rollover line for a new extension on a Mitel 3300.
A little background...I'm not very well versed in telecom, but at my workplace the management of the phone system has fallen to me. We do have a vendor that manages our phone system but some of the simpler tasks have hitorically been done in house.
The problem...I've created the new extension and assigned it to an IP phone and it works (surprise!!) But there is no rollover line, forgive me if I am not using the correct terminology here. To explain what I am referring to, if the user is on the phone a new call into that extension will go to the secondary line. Other phones in my environment have them set up as, for example, extension 1122 the rollover line is *1122. I cannot figure out where I create this *extension in MCD.
Any help is appreciated.

 

[SXWizard]

In the Keys tab of the User and Devices form for the new extension program button 2 as a Multicall key with the extension number of the prime line. Then if the prime is busy the Multicall will ring. You can choose a Ring Type of Ring (will ring once if prime is busy) or Ring Cont (keep ringing until the call is answered or sent to voicemail).