Hello,
You will need to edit the Forms.
To do that head to "Application & User Management" work center and then select "Form Template Management":
In there you will have access to all forms (Accounts summary, Appointments summary etc.), just look for Sales Quote:
Hopefully for your template you can use the Easy Form Editor feature, otherwise you need to download Adobe LiveCycle from the Download center in C4C. It is ok for Sales Quote:
From there it's really straightforward, you have the default sections and the fields already activated in the Services.
Also to see your extension fields in there, you need to go in "Further usage" in them and activate the proper Service used for the Form Templates. I am not sure which one it is for Quotes but it shouldn't be long to figure this out.
For any advanced modification on the form, you will need to use Adobe LiveCycle.
Hopefully this will be helpful,
JB.