would like to know how I can proprely shift a 6speed eaton transmission on a International truck

by Alain
(Montreal, Qc, Canada)

Have a lot of problems with the shifting, When is the best time (rpm and speed) to shift gear? What do I have to do to avoid grinding on gear? My truck is a Inter 4300 6 wheels with an Eaton-fuller 6 speeds Transmission.

Any tips for me???
thanks
alain