I'm going to have to guess at what you mean by a "slave" drive, because the terms Master and Slave referred to EIDE drives and, as far as I know, no-one is making EIDE SSDs.
I'm going to address your questions out-of-order; sorry, but it makes it easier to write.
Once the disk is attached and can be seen in the BIOS, you have to partition and format it. See the relevant steps here:
http://www.tomshardware.com/forum/265764-32-guide-installed-disk-system . Now, the drive will show up as a new drive letter on your PC.
To back up files to it, you choose your backup method or software and use the SSD as the device for the backup. This is, however, a hideously inefficient use of your fastest drive. I would not recommend it.
What most people who get an SSD do is to do a fresh install of Windows 7 on the SSD, re-install all their programs, and keep their data on the normal HDDs. That way, the operating system and programs (games) run from the SSD which has very fast read rates, and everything loads more quickly. There are plenty of articles and threads on how to do this here on Tom's.
If you really want to stick with your current OS installation and install your games on the SSD, you have to see if each game's installation process allows you to specify the install directory. If it does, you specify a directory on the new SSD. If it doesn't, you are SOL.
BTW: For further discussion, what model SSD, how big, what OS are you running on how big a hard drive? This will help people figure out how things should be balanced.
Have fun
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