Backup for OSX to transfer to El Captain

I have a desktop Mac and am running OSX 10.9 and want to back everything up before I update my operating system to El Captain.
I gather I have to reformat the WD Passport Ultra to use with Mac, I have read the instructions and it dosnt sound too easy!
Will I then be able to transfer the information to El Captain if needed?
Can I then use the Passport as regular backup with time machine?
My last external was just a plug in and connect to function but at 500Gigs now to small.
Help!

Hello,

In order to use the drive on Mac you first need to format it for Mac. Then you can just use Time Machine in order to create your backup.

Thank you.
I am now backing up. When I look to see what is backed up it tells me that it has backed up movies, (purple ) but no pictures (orange)
When I try to open IPhoto picture in my passport it just tells me that it is a back up version and can’t be used as a main lib ray, I get that, but wont open via time machine/passport. Should it?
Can you help me with this or shall I repost
Thank you