should i put this in the radiator and the coolant tank on a 97 chevy silverado z71?

[shut up and train!]

yeah i just ran my truck around the block to get the engine warm
it keeps saying its overheating
so i popped the hood and the coolant mark wasnt up to the hot line
so should i drain the radiator, follow the instructions on the bottle
and then put this in that coolant tank thing?
i have this stuff, i found it behind the back seat yesterday
http://www.amazon.com/Honeywell-AF2100-Antifreeze-Coolant-Prediluted/dp/B0016GRWJY/ref=sr_1_3?ie=UTF8&s=automotive&qid=1244562573&sr=1-3
or should i just put it in the tank? the bottle says to drain the radiator
put some water in it
let the truck run for 10 minutes to circulate
then put this stuff in it for 10 minutes to circulate and idr the rest
how much should i add in? till its full or something?/
are those expensive? and i cant do this right now, my ****ing mom is making me go with her somewhere even though i dont wanna go...
i have shit to do...i have to do this, build a grill and put a new radiator in my other truck
i have a similar prob with my other 97. it has a 502 big block tho...i need to replace the radiator today so i can drive it i miss the speed and insane power
i havent drove that truck since i got this one