Halloween // Advice for growing giant pumpkins?

So my mom accidentally bought two giant pumpkin plants (I think she said they're supposed to get up to 500 lbs?) and we both have no idea what to do with these. She planted them but...do they need special care or anything? We live in the PNW so it rains a fair amount if that has any impact.

I've only grown jack b littles...and out of the...idk 20 seeds I planted...I got three tiny jacks. Like...super tiny...stunted. I'm not good at growing anything lol.