Why would you need separate partitions for big and small files..?
I mean, you definitely could, but all you really have to do is set where to keep your actual Documents and Video folders (for example). The way Windows 7 does it is that you can keep those folder links where they usually are (C:\Users\echod\Video), but set it to store the actual files in a different location (A:\Videos). It's not really necessary to create separate partitions unless that's really how you prefer to organize your files, but it's just as efficient to have separate folders.
If that doesn't make sense, I personally keep all my Videos, Pictures, Documents, and all that stuff in their own folders in my hard drive so they don't take up space in my boot drive. I didn't have to create separate partitions for them.
I'm assuming they say to turn off backup so you don't keep writing files to your SSD, which decreases its lifespan. I don't see anything wrong with backing up your SSD files on a hard drive though. Just go to your Windows search bar and type "partition", and you should see a result saying "Create and format hard disk partitions". That should allow you to create a separate partition to keep your back up on (in your HDD of course, not your SSD), though even that's unnecessary, because I'm pretty sure you can keep your backup in a folder in your HDD's main partition too.
Hope that helps.