Another Heater Question for Impalas!

I have a 2006 Chevy Impala LS.  Whenever I am idle, there is no warm heat blowing out of the vents, only cold.  I have researched on here and read a few other questions relating to the same problem, their solution was to replace the thermostat.  I had bought a brand new thermostat and switched it out yet I still have the same issue.

Another solution was to bleed the cooling system which was explained to me as:

"rev it to 2500 rpm for 40 seconds, then idle, top off the fluid, and repeat 2 to 3 times. then shut the engine off and allow it to reach room temperature while you chugg a few alcoholic beverages. come back and and top it off. it should be purged of all air. if it is still too cool, more than likely you have a thermostat that is stuck partially open, but should be accompanied by a P0128 for engine coolant temperature below thermostat regulating temperature. good luck email me if you have additional questions."

I have not had any engine lights come on at all.  Also, when it mentions to "top off the fluid" does it mean Engine Coolant?  As in, pouring it through the radiator nozzle?  I know this seems like an elementary question but I am new to this, a bit hard pressed for money, and trying to see if I am able to do this myself.

Please, any help is more then appreciated.