Please Help!

It may sound stupid, but i have a problem.
I bought a fuel injector cleaner, the liquid, and the guy in the stre says that its pretty good.
on the can it says to put 1/3 of the liquid in the manifold vacuum line and run the car for 5 min.
the problem is i dont know where is manifold vacuuim line.

please somebody who knows how to use it or can derect me how to find manifold vacuum line help me.

my car is nissan sentra 2001

thank you guys for your help

i thought that nissan had self cleaning fuel injectors, so there would be no point in buyin the fuel injector cleaner. fugiot/sideways...is this true?
btw, which model sentra do u have? GXE, SE, Spec-V? i remember reading about this in a past post.

2001 and you are trying to put FI cleaner already? you dont need to at all. i havent been able to confirm or deny the self-cleaning injector problem, but i have never heard of nissan injectors gunking up.