One cable will connect a notebook or tablet to the projector in all rooms. That cable is an SVGA monitor cable with audio, and you must bring one with you to the room. This ensures you don't find the cable missing, or a cable with bent pins from the previous presenter. Cables may be purchased locally from Cables and Connector Technologies. Don't use a longer cable than necessary. Length affects picture quality. Here is a picture of the entire cable.
This cable has a male 15-pin video connector (note the "D" shape) and a 3.5mm stereo plug (male) on each end. It does not matter which end is plugged into the computer or the projector connection panel, but one end may reach the notebook connections better than the other. Here is a picture of one of the cable ends.
All projector connection panels have a matching female 15-pin-socket video connector labeled "VIDEO" and a 3.5 jack (female) labeled "AUDIO." Panels vary in appearance. The notebook or tablet has the same connections. The male connectors and male plugs are inserted into the female connectors and jacks, orienting the D shapes of the former. The thumbscrews on the video connector are tightened clockwise. An easy way to remember is "Righty Tighty, Lefty Loosey." Please do not overtighten. They only need to be snug.
The projector is turned on or off with a "Power" button, which may be labeled with this symbol. 
It may take some time to reach full brightness. Audio volume is controlled by "Volume" Up and Down buttons. Don't forget to also turn up the volume on the notebook or tablet, if necessary. Depending on the room, the Power and Volume controls may be either on a projector control panel or a remote control with a security cable. The remote control looks like one for a television.
The remote controls may have an On/Off switch to save their battery power. You may have to turn the remote control on. Please remember to turn it off before you leave.
Some rooms have multiple projector input panels, one of which is labeled "Computer." It will have the female connections discussed above labeled "Video" and "Audio." There is a button near the "Computer" label to cause the computer to be selected as the projector input.
Different notebooks and tablets use different key combinations to switch between showing the image on the notebook, the projector, or both. Consult your computer's user manual for which ones to use. It is often a key labeled "Fn" in blue lettering, and another key with a blue outline of a computer screen. Press and hold the "Fn" key, then press the other appropriate key, then release the keys together.
Please remember to turn off the projector before you leave. The bulbs are very expensive and have a much shorter life than household bulbs.