"Insert your Windows installer disc and wait a few seconds for the disc to be recognised." burned the iso to a dvd with disk utility.any ideas please?

hello eveyrone.I have been stuck to the above msg for the last 6hours . Kind of frustrated after spending all day reading here and there.

I have a macbook pro ealry 2011 (10.9.3) new ssd 1t samsung.and trying to create a bootcamp for windows 7 (90 days free trial).

Allowed Boot camp to download drivers onto my external usb.

Burned iso file to internal dvd as image and still get the above...any assistance please?