From the launch pad activate your first stage, and turn SAS on, from here just drive your throttle all the way up.
Now for the important part. When you get to 11k meters above Kerbin, deactivate your SAS and turn your ship to face 45Degrees west so that your ship is facing the number 90 on the blue hemisphere of your navball, activate your SAS again once you have the right angle.
This rocket is built so that the Jumbo will run out of fuel at nearly the perfect time, but idealy you want to cut the mainsail engine when your Apoapsis marker hits 110k meters above kerbin. This number does not have to be exact at all.
Move on to your next stage and cut your engines. Now open your orbit map by pressing [M] and locate your Apoapsis marker. Accelerate time until you are getting near that marker and bring time back to normal speed.
Turn your SAS off and aim your ship before hand so that it is 45Degrees further west so that your ship is facing the line in between the blue and orange hemispheres and activate the SAS again. Next, right when you hit the Apoapsis marker, throttle up all the way.
We are in the home stretch of getting into orbit, open your orbit map and given you have followed the instructions, your trajectory arch should be getting wider and wider. Continue burning until the arch becomes a nice circle around the planet and then cut your engines.
You have just achieved orbit!