Deep cut on thumb what shall i do ? HELPP!?

ok so on monday in art i was using a lino cuter for my work i got distractedan and stabbed it write in my thumb , i put my other hand around it and when i took it off it was bleeding like hell ! i went to the sink and washed my hand and went to the office to get a plaster . when i got home it was throbbing like hell to i cant even use my thumb proply it looks like nothing but it really hurts,right now i have got a small bandage on my thumb but it its still throbing ,iv got school in 1 hour ,should i just keep the bandage on ? thankss