Once you enter test chamber 6-6 turn to your right and place a portal on the white wall and another on the ledge to the top right.
Once on the platform with the red button which controls the vent. Place the portal from the higher ledge under the orange gel tube. This will make a running platform. While staying on the button put one portal on the angled ramp, and the other under the white gel.
Once you have created another portable wall put a portal on this and your other under the blue gel, this will spread to the small square platform in the middle. Now put your portal back on the tilted ramp and the other under the blue platform (remain on the button)
Once this is done remove the portal from under the gel tube and place it at the end of the orange runway you made. Run through your portal and bounce off the platform, against the wall, then back to the middle platform and up to the exit.
Video Guide starts 0:25