my boiler\\\'s in the red!

when my c/h is off the pressure drops to 1 or below, so i\\\'v filled the system back up to 2 and bled the rads to make sure there is no air trapped, which there wasn\\\'t. when i\\\'v turned the c/h on the pressure goes upto 3 stays there for awhile and then slowly drops to 2 . when the heating is turned off again the pressure drops down to 1 or below again. i have a potterton puma. can anyone help. please dont use too much jargon in your reply as i am female!

The system should be filled when cold to the pressure specified in the manufactures instructions. (Probably around 1 - 1.5 bar without checking the MI).
It is normal for a slight increase in pressure when the system warms up. However is the pressure is going in the "Red", you probably have a fault with the pressure vessel.
The pressure vessel can be recharged with a car type foot pump.
You can test this by pressing in the valve when the system is cold, if water comes out or you don't hear any air then it can probably should be recharged.
If you are not comfortable checking this, please call out a heating engineer. The pressure vessel and pressure relief valve are saftey devices and the system can be dangerous if they are not working correctly.

I agree. Check outside the house, there will be a pipe coming out behind and below the boiler- when the gauge goes to three, water will come out here. if so, the expansion vessel is at fault. it may be possible to pump it up again with air, or it may need to be replaced. It's definitely not a DIY job, call a Corgi reg boiler specialist.