How to unclog heater core myself?

What is your question?

5.3 l engine TrailBlazer overheating. Heater blows cold and doesn't blow at all on max. I hear water swishing in dash. And fogged windows, coolant inside passenger floor. heater core hoses are underneath and behind AC condenser, I fixed a cracked hose ( no leaks ) which already has a flush kit installed. I need a video or pictures, someone to walk me thru how to flush heater core?

What makes this problem better or worse?

Worse longer I drive it

How long has your 2006 Chevrolet Trailblazer EXT had this problem?

Nearly 6 mos