gas fire and winter

hello people. things are rocking with our van...we've done plenty over the summer...we bought it mainly to travel to triathlon but we've found ourselves just going away for the hell of it....but sadly...winter is approaching ...and last weekend i tried for the first time to use the gas fire...well i didnt really...cause i never turned on the gas...i just wanted to know what the electric button that says carver (same as the fire) does....and if i need to switch that on before i can light it....when i did switch it on...a little alarm light came on...is this because i hadnt turned on the gas??

also...can somebody give me a quick run down on how to winterise it?? do i just not use any water through the pump if i take it away with me through winter???

cheers