How do you shift eaton 6 speed transmission?

It's a synchronised transmission, much like any you'd find in a regular passenger car. You push in the clutch, shift the lever to the next gear position, and let off the clutch to engage. Up and to the far left is reverse. There is no gear position immediately below reverse. To the immediate right of reverse is first gear. Below that is second. Up and to the right of that is third. Immediately below that is fourth. Up and over to the right once more is fifth. Immediately below that is sixth. There should be a diagram of the shift pattern either on the knob or on a panel somewhere in the vehicle (if it's not visible on the dash, try the sun visor).