How do I connect the laptop to the projector using Power Point.

Connect the data projector to the video port on the laptop. Then power up the data projector and then the laptop, the video data will automatically be diverted to the data projector.
If you want to see the Windows image on your laptop screen as well you need to press and hold down the FN key plus one of the function keys on you laptop which has a screen symbol. Pressing this key will toggle between the laptop screen, data projector or both laptop screen plus data projector.
You can open Power Point and select your presentation as you would normally.