I have a toshiba docking station. I have an external monitor connected to my docking station. I cannot get this to connect to my mac pro. How do I extend the desktop to the monitor via my docking station??
Laptop docking stations are often specific to a particular brand or model. If it uses USB to connect, as Shinrai asks in the comments, it's possible you could get it to work by downloading the proper DisplayLink driver for OS X, but that will only work if the adapter chip used is compatible in the first place.
You may want to just directly connect the monitor to your Mac — it will likely result in better performance and reduced CPU utilization vs. connecting it through a USB adapter. Depending on your monitor's connections, you may need a mini-Displayport to DVI or HDMI port (or full-size Displayport), which you can find in various places (I recommend Monoprice.com for cheap but reliable ones).