Where does a referee stand on a soccer field?

By referee helper, are you referring to the man on the sides of the field? If so, then you are talking about a linesman.

[EDIT]

According to the LAWS of the GAME pubished by FIFA. The "referee helper" and "linesmen" are officially named "Assistant Referees." In some matches another official, the "Fourth Official," is responseable for recording match information, maintining order of the bench area, subsitutions, and other responsabilities given to him by the referee.