TAke it to a garage as there is a leak and it may need new parts. Bleeding the system is very hard also.
on your clutch pedal
on the clutch pedal lever
sounds like your slave cylinder is bad or your clutch, find your clutch fluid reservoir and see if its full ,if not look for a leak if there is a leak most likely that's the problem and needs replacing.
To the right of your gas pedal under the dash
If a 1989 Nissan Sentra clutch pedal quit working and the car is now stuck in reverse, it will need to be towed to a repair shop to fix the clutch. The transmission may also be damaged due to it being stuck in reverse.
You will eventually lose clutch pedal pressure and the car will refuse to shift into gear.
behind the panel next to your gas pedal
It gives the clutch pedal a softer, smooth feeling. Some people remove these for a more direct pedal feel
If you are referring to adjusting the height of the pedal, I might be able to help you get started. If you can squeeze under your dash to where your pedal is, there is a stopper bar behind the pedal that can be adjusted by first loosening the washer that holds it in place and then turning the bolt until you get the pedal where you wish it to be. This is what i did for my 95 maxima, and I assume it is the same. If you are referring to adjusting the height of the pedal, I might be able to help you get started. If you can squeeze under your dash to where your pedal is, there is a stopper bar behind the pedal that can be adjusted by first loosening the washer that holds it in place and then turning the bolt until you get the pedal where you wish it to be. This is what i did for my 95 maxima, and I assume it is the same.
Maxima comes with Auto adjustments. All you need to adjust is brake pedal free movement.
The clutch Throw Out Bearing is going bad.
You can find the flasher relay on Nissan Hardbody on the metal flange of the clutch pedal.