Lost green tree frog named Charles with yellow spots at Riverwalk Park, Terre Haute.

I lost my pet green tree frog named Charles at the Riverwalk Park in Terre Haute. I took him out for a bit of fresh air, and he jumped out of my hands while I was trying to take a picture. He's about the size of my palm and is bright green with little yellow spots. I'm really worried and would love to get him back.