This is how I replaced an inline fan above a bathroom. Apologies for the poor camera work but I wasn't expecting to video this and didn't have a tripod with me. In case you wonder, I did clean the ceiling grill!
The LT is for models with a timer and will come from your bathroom light, so when the light is turned on, it triggers the fan to operate. The Live will then supply power when the light is turned off so it can then run for as long as the timer permits.
