I have no clue what to do!! I am using a wilton pan that is 11x15 and the middle isnt baking. What do I need to do???

What recipe are you using? Box or scratch? How much batter used? What temp are you baking at? How long? Are you using bake even strips?
You'll get some people saying that you need anywhere from 1 to 10 flower nails to help the baking b ut I have made that size cake w/o any for over 30 years and not had problems.

You probably need to bake it longer but using a couple of flower nails as heating cores will help.

Please explain the flower nail process. Do you place it head down in the pan and then pour the batter over this?

Yes - head side down.

Spray the flower nail with non stick oil (I use Baker's Joy) so the cake won't stick to it.

For that size pan you will only need one flower nail.

I bake at 350. Ater the first 20-30 minutes I will then start check the cake with a toothpick in several places until the cake is done.

I usually don't use flower nails ( I always remember to use them as I'm pouring the batter) But I bake at 325 and just bake longer. I don't even check for done-ness until I can smell cake through out the house, works like a charm.

I've never used flower nails or bake even strips or any of that. Just lower the temp, and bake it longer.