The very first thing you should understand is that most computers have different BIOSs and different BIOSs use different ways to enter setup. But all of them show brief prompts about what keys to press.

So, the only thing you should do is to find that prompt and press according key.

As soon as you do this, you'll go to BIOS screen:

Although BIOS configuration depends on the version, but the architecture is always the same. There are few sections, that are alway present: Boot, System and Advanced. Also there are always prompts that show you how to navigate and change values.

To disable SATA Native mode go to Advances section and look for SATA option and set it to Disabled, or Compatability mode.

To set boot priority go to boot section and set First boot device as CD-drive.

If you don't fin'd these options there look in othere sections. There are no BIOS without there options.