I would suggest opening the top and look down inside to see how much debris is in there first. Vacuum the big stuff out, then test the drains with a cup of water to see if they run clear. If they back up, then you need to fix that first. Follow the YT link;
https://www.youtube.com/watch?v=Hz-C9pkMnDk
Otherwise, wash the rest of the car normally and sponge bath those two areas until you sort it out?