sunless tanner?

ok so im gonna be in a wedding tomorrow and its a strapless dress i have like tanning issues so today i went to the store and bought this bananna boat airbrush tan stuff but it doesnt to rub it in do i just spray it and thats it or should i rub it in? and do these things work? am i going to be patchy?

it gets patching sometimes look in the mirro befor you go =]
i bet it will work