Here is a great video to show you how to use a CO2 pump for your bike.
CO2 pumps can seem daunting to use, compressed gas in a tiny canister conjures up scary exploding situations, However it really is quite safe if you follow some safety rules. This GCN video will help explain what to do.
There are a large selection of CO2 pumps out there, some small and some are tiny. They all work in quite similar ways, and they are all small and light.
Make sure you don’t setup the CO2 canister until you need to pump the tyres.
CO2 canisters can freeze when activated to pump the tyre, some pumps have an outer sleeve for the canister to help with the freezing or a case to hold the canister to greatly reduce freeze contact to your hands.
There are 3 types of CO2 canisters, threaded or non-threaded. But there are some pumps that can take both types.
Typical canister sizes are 8 oz, 12 oz and 16 oz, the 16 oz canisters should be enough to pump up 2 wheels for your road bike.