The 3i SDC is controlled via SlideBook 6. 
The user manual can be found here.
To locate your cells, first choose your objective, and appropriate sample holder for your samples. Once your sample is appropriately placed on the stage, you can move to the software.
Click on "Focus" to bring up the controls.
In the focus window, under Filter Set, select Widefield. Open the shutter for a light source, and select the appropriate filter for your sample. "Open Fluor" opens the shutter for the fluorescent light source, and "Open Brightfield" opens the shutter for the transmitted light source. "Open Alt" opens the laser shutter and isn't useful for looking down the eyepiece.
To use the spinning disk to view via a camera, select an appropriate filter set. There are different sets for the two cameras. Most people would use one or the other camera and not both at once. The 95B is more sensitive than the BSI, but it has larger pixels and hence lower resolution.