Where do you go on the FDICs website to see if a complaint was filed against a bank?

Is this in reference to an application to buy, sell, engage in a merger, etc.? I don't think those complaints are public.

And if you mean the complaints that you need to include in your public file, you would already know about those. You don't have to hunt for them. They would have been shared by your regulators or received directly by the bank.