I have tried to post an add to sell my boat a few times now. I fill in everything and choose the 90 day run and when I hit submit it shows everything is uploading but the next screen i get is a blank of the one I just filled out with the boat info. Never takes me to a payment page. Not sure what I am doing wrong.

Are you posting pictures too? The files might be too large. Try resizing your photos to 1024 X 768 in pixel size.