The 1st Step is to create the CAB under "Processes -> Change Advisory Board"
Next create the approval process under "Processes -> Approval Processes" Choose the options appropriate to your requiremnets
Click Save and then move to Approval Steps, here you will define the Approver Type, in this case it will be a CAB, choose the name of the CAB you created.
The final step is to choose which requests types will initiate this process. Click the "Request Types Supported" tab, select the required request types and click save
Hope that Helps,
Thank you so much! This definitely helps.