Walk to the door to let in Wheatley, your new partner.
Try talking to Wheatley to learn how to Jump (Space Bar).
Wheatley will move the room around. Don't worry, it's impossible to fall out.
Jump out of the room and onto the broken glass to enter the testing area.
Step through the Orange portal to come out of the Blue portal. This works both ways.
Pick the Cube up with E and drop it on the button by pressing E again.
Enter the elevator at the end of the puzzle to go to the next level. This is now a given, and will not be explained again.
Push the button next to the room you want to get into to make a Blue portal appear in it. Use the Orange portal at the back of the room to get through. Get the cube from the first room, take it to the button room, and then open the portal to the exit door.
Go to the podium in the middle of the room.
Oops, you fell through the ground. Progress forward to find the Portal gun v1. This Portal gun can only make Blue portals that connect to Orange portals. Shoot a Blue portal on one of the white walls and keep going.
Place a Blue portal on the wall next to you to get to the platform with the Orange portal. Then, shoot a Blue portal near the exit door and walk through the Orange portal.
A cube will drop in the hole. Jump down into it, shoot a portal in there, and take the cube to the button.
There is a cube in the hole in the back of the room, do the same thing as last room to get it out. To get the second cube, go through a portal to the platform where the orange portal is at, then shoot the blue portal behind the second cube. Walk through, grab it, and place both on the buttons.
Now you are trapped in a room. Shoot a Blue portal on the wall so you can escape onto the roof.
Place your portal under the left cube dropper and press the button behind the pressure button. The cube will drop through the orange portal, put it on the pressure button and walk up near the exit.
Place your portal under the second cube dropper, and press the button for that to drop a cube. Wait a few seconds and press the other button to raise the ground to prevent the cube from flying into the water. Grab the second cube and place it on the button by the door.
Portal yourself out of the starting ditch into the room. Place your portal at the centre of the hole in the middle of the room. Jump through it from above to fling yourself across the room.
Shoot your portal through the hole under the cube to free it. Jump back down, set up the fling jump again, and jump through with the cube. Put the cube on the button by the door.
Welcome to advanced flinging! Now the Orange portal is in the hole, and you need to place your blue portal where you want to fling out of. First put it on the ramp to the left of the room (from entering). Fling through the portal to land where the cube is.
Place your portal up on the wall on the right (from entering) and jump through with the cube. Place the cube on the button that is up there to make a platform in front of the door. Jump through the flinging portal again to land in front of the exit door,
No puzzle in this room, place your blue portal in the other room and jump through to your pal Wheatley. After he drops down, pick him up and put him in the wall terminal (be sure to turn around, he's doing some serious hacking).
Pick Wheatley back up and take the new route behind the test chamber.
Make your way through Glados' messy chamber to the back behind the incinerator. Jump down from the stairs and continue walking.
Enter the control room and help look around for the right Switch. You won't be able to find it, so plug Wheatley in when he asks.
Plot time! Wheatley accidently awakes Glados, Wheatley gets thrown away, and you get dropped into the incinerator!
Thankfully you survived the fall, progress onwards to find the Dual Portal gun!
Now that you have the Dual Portal gun, you can place both portals. Use this to get past a few obstacles and back into the main tests.