Starter ship environment issue

Sorry if this is common question, but the answer eludes me. Right after first undocking, any thruster use says, “I’m too heavy to move”, and I end up dying in just a few because of o2 or co2 or n2… I dunno. Do I have to wear a suit? Am I supposed to fill the canisters of gas? Where? My ship is small and seems in perfect order. I cannot find any switches to turn on that arnt already on “auto”. Also, every thrust use causes a weird zoom in, zoom out. I feel I’m missing something simple.