OK. For Caravan and Camping use, RED bottles hold Propane, and Blue bottles hold Butane.
If you already use Butane, you will need to change your regulator (at the end of your gas hose) to use Propane, and vice versa. The regulators are different for each gas.
Most modern vans run on Propane, and it's readily available at all caravan dealers who will also make sure you get the correct regulator. The regulators are simple to fit, but if in doubt ask the supplier.
Propane regulators have a Left Hand thread, so tighten up anti clockwise. Once you have fitted it to the bottle, turn on the valve fully, and then back about 1/2 a turn. this avoids undue pressure on the valve seat. There is no need to open and close gas valves like having a strength test for Godzilla.
Smell around the valve and if you have done it OK, there will be NO smell.
Hope this helps.