You do not need an import license to import shoes into the USA - generally speaking.
If the shoes are made from an endangered species, the U.S. Dept. of Fish & Wildlife will be interested and will require some formalities.
Otherwise, you will only need a "Shoe Report" from the manufacturer listing all the materials the shoes are made of - ie. leather, pig skin, rubber, glue, etc.
For any questions about importing, you can either call a Customs House Broker (recommended) who can assist you with Customs Clearance and regulation, or for small shipments valued under US$2,000.00, you can clear the goods yourself through customs, with proper documentation.
Please see the references below.