Whirlpool door not sealing

My house has become VERY humid. I couldn’t figure it out, but when I opened my refrigertor door, it literally slide open, no seal. Inside there is condensation. I looked and all the food is back. When I looked at the seal, the bottom outside seal doesn’t even touch the refrigerator.

  1. If I buy a gasket (expensive), do I need any tools to remove and install the replacement?
  2. How do I replace it?
  3. Do you think that might be the fix?

I know you can’t see it. I don’t know appliances (just computers), but it is the only "moisture" I can find.

Thank you.