Hi there and
to the forums
You've been given great advice so far concerning your new budgie
By now, the messiness around the vent should have cleared up about now if it was purely stress related. As he settles in, he will begin to explore more and move around more, as well as gradually play and eat in your presence.
Always take things at his pace, no matter what. Soon, and with patient and gentle work, I have no doubt he will begin to be more trusting in you.
During the few weeks of his "settle in time", it's great to have some reading time or just sit by his cage to talk to him or do whatever you have to do as he will get used to your presence
Be sure to read through all the great resources and links provided by FaeryBee as they will help you to start to learn lots about budgies and the best ways in which to care for them! If you have any questions afterwards, please do ask as we'd love to help.
Hope to see you around, and don't forget to share a picture or two of your little one when you get a chance!