i dont know how to explain this,, but in some of the videos i watched, i can see ppl controlling their units to move in consecutive designated positions.. its like they preplan the actions of the units and the units just move accordingly. lol see the pic below.. does it even exist or my mistake ?lol

Shift right click to queue commands

yep, its called waypoint.
hold shift and right-click to set a waypoint. You should see a green dotted line while you hold down the shift.

how about queuing buildings? i see b4 the unit is probe, then build pylon at 1->2->3->4

same thing,

select the building you want to build, then hold shift and click on the spot you want to build.

shift does all the queuing command things.

Shift queue up commands, whether it's movement, attack or buildings.

wow.. cool .. thanks for the answers .. the word waypoints didnt came across my mind =.=;;