At first I was struggling to get my Toshiba Hard drive to appear (so I could use it) on my MacBook Pro (as I wanted to put all my photos, iMovie videos etc on there) so I eventually found a way by going to my settings and clicking time Machine and so on. Now that everything from my MacBook Pro is on the Toshiba hard drive, I plugged it into a Windows laptop (so I could put my photos etc on there) and it doesn't even pop up so I am unable to access my photos etc on there and put them on the Windows laptop, but when I plug it back into my MacBook Pro it shows the hard drive with all my pictures etc on there!
If you have this drive set up as a Time Machine backup, this means that you have formatted it as HFS+, the Mac hard disk format. Windows can not usually read this format.
The problem is that if you change the drive to a different format, it will mean that you need to put all the data back on it afterwards (reformatting a drive deletes everything on that drive), and you will also not be able to use that drive as a Time Machine backup in the future unless you put it back to HFS+.
If the two machines are on the same network (WiFi or wired network), you can share the drive from your Mac and connect to it from the Windows machine, then copy the files that way. Over WiFi this could take a while.
If you're using Time Machine on the disk, the disk is Mac OS Extended formatted which can't be read by Windows without additional software.
You can use the Boot Camp drivers which integrates HFS read/write into Explorer.
Alternatively, you can use HFSExplorer: