Partitioning on Macbook Pro (PLEASE READ)

Hi guys.

I am somewhat of a novice to the Apple Support Community, so bare with me and I am sure by now that some of the veterans of this forum are used to this topic cropping up but I have yet to find a solution so I need your help guys.

I have bought a copy of Windows (8.1) online through the Microsoft website (UK), only to receive an email with a product key and a download link. I tried both the download link and attempting to download the OS from the download option but naturally it was not a format which is compatible with OS X. The aim is to partition my Macbook so I can switch between programs for Windows and Mac appropriately and I have given a couple of websites which provide instruction on using boot camp a flick through, but have only been left more confused and unsure about how to go about doing this.

Last night I browsed through the Apple guide to boot camp, in which it stated I could use an ISO image on a memory stick in conjunction with boot camp to partition my hard drive and install Windows. However, I am a bit confused as to how I should set up the ISO image and how I should carry the image on from the USB to my MAC via boot camp.

I am an absolute technophobe and really need help with this issue! If anyone could lend a helping hand to a fellow Apple user I would be very grateful!

Thank you