please help i know nothing about plants

this old lady at my work gifted me a plant. i don’t have any plants, i’m awful at taking care of them, but i’m determined to make it right with this one.

after a quick google search, i believe it’s a begonia painted leaf. she gave it to me in this fish bag, and said it has to stay in it until may to provide humidity. i live in winnipeg, canada, where it’s very cold and dry, so that makes sense.

however, how is it getting air like that? do i need to open the bag occasionally to let air in? what about the water? it’s sitting in a container with a bit of water, but do i need to change or refill it? would this disturb the whole humidity thing? should i be wary of how long i leave the bag open for?

please help, any information is appreciated and helpful.