System Preferences. Time Machine.
System Preferences is something you should know about if you do not. You can access it from the Apple Menu, and it is a default item in the Dock.
I have no idea where there are screen shots.
There's one slider and two buttons. Not really a lot to look at, or be confused by.
The slider says ON and OFF.
One button says "Select Disk"
The other says "Options..."
If you wish to select a disk, choose "Options..."
Just kidding.
There are no "magical options."
For Step by step instructions:
To turn on Time Machine:
1. Slide switch to On.
To turn off Time Machine:
1. Slide switch to Off
To select a disk to use:
1. Click Select Disk.
2. Select a Disk.
To Remove a Disk:
1. Click Select Disk.
2. Select Disk.
3. Click Remove Disk.
To exclude Items:
1. Click Options...
2. Click Add ( + ) button.
3. Select folder to exclude.
4. Click Save.
To remove items from exclusion:
1. Click Options...
2. Select item
3. Click Remove ( - ) button.
4. Click Save.