How can I install motion detector lighting?

Check the setting on the light themselves. Do you know what brand light it is?

Do you want to install a motion-sensor light fixture where a regular light exists now?

or

Do you want to install a motion-sensor light fixture in a location where there is no light now?

Indoors, or outdoors?

We have a motion light in our backyard. The sensor itself is visible while the power switch is on. If you mean the light remains on and doesn't shut off, I have had motion lights that had a switch on them for continuous light. Check yours, and you may find a switch in the wrong setting. It will probably be near the socket. If you know the brand, look online for a direction manual. I had a light I thought was broken until I read the manual.

If you wish to install a motion sensor light, the easiest way is to put up a solar powered one.