i have a recently bought 15 inch 2014 Macbook Pro with Yosemite but does not have a CD/DVD drive. How do I create Windows 7 on a usb flash drive so i can use it to install bootcamp?
I moved your post here to the correct forum. It's not a "Switcher" subject. Now to answer your post....
Burn the Windows 7 DVD (preferably the 64 bit version) to a USB flash drive as an ISO. Make sure you burn it correctly so that it's a bootable ISO. After that, follow the Boot Camp instructions for your MacBook Pro. You will also be required during the Boot Camp setup to download a driver image from Apple. You likewise need to place that driver image on a USB flash drive.