I got a 2011 ford fiesta SE and would like sirius....?

Yes, a Ford dealer has to order and install it. It sounds like the module will cost $900 (it is always way cheaper to get the car with everything from the factory). If that's too much, you can buy an aftermarket receiver and attach it to your dash for about $100. Depends how much you value the integrated install. Step one is to ask your dealer if they can get one. I would contact a few dealers.