I have OptiPlex GX260.

Because there is no internal DVD drive installed I have external Samsung DVD drive.

Question: 

How can I get my computer to recognize my external DVD drive

and install my Linux OS from the disk in my external drive?

My BIOS:

Primary Drive 0:  Hard Drive

Primary Drive 1:  OFF

Secondary Drive 0:  CD-ROM Reader

Secondary Drive 1:  OFF

Thanks,