Brandi,
Welcome aboard. I did not mean to come off abruptly, it's just that I see many new members join up and the first thing they do is ask questions about rectifying a problem before even telling us what they're working on, etc....then you never see them post again.
First off, I commend you for wanting to do the repair on the car yourself.
You're in good company here, and there's many good people who are more than willing to help.
To access your speedo cable...I'm assuming the speedometer end. You'll need to remove the plastic bezel around the gauge cluster, them unscrew the small self tapping screws that hold the assembly in place. Once everything is loosened up, pull the gauge cluster back...don't force it if it doesn't come out easy. It will need to be pulled out far enough to be able to get your hand behind it to unsnap the clip holding the cable to the back of the speedometer.
I'm sure other guys more familiar with an Olds cluster configuration will chime in.
Again, I'm assuming the problem is at the speedometer end.