Time Machine

I lost a few important files on my iMac and never got round to setting up time machine so now I will.
I am running Yosemite and googled set up but have found lots of different threads so not sure of what I should or should not do.
If anyone can point me in the right direction it would be appreciated and myself and other half both use the Mac and have different log ins, so if I set it up for me will it also back up her info ?
Thanks.

 

Ok will do