CO2 and humidity in separated sensors

I'm a food engineer who can barely understand programming, but I have to work with arduino to make a system that can register the permeability of a plastic membrane, I need to use arduino, but I have no idea what sensors I should use, or how to program them. Please help :c :( :( :(

I'm in Guadalajara, Mexico, but I guess I can get the sensors on the internet if I can't find them locally. Thankssss!!

Why seperated? co2meter.com has some neat sensors that do both in the one package.