You've already gotten two great pieces of advice, so all I will offer in the meantime is good luck and have fun! Even though I feel easily self-conscious too, I think you should be celebrated for learning to ride a bike as an adult! I know I certainly am happy for you and proud of you, and I bet others will be, too! Besides, most people are too concerned with their own worlds to care very much about what goes on around them.
You ride that bike and rock it. I hope you have a great time and yes, definitely make sure your feet can touch the ground! A properly adjusted bike is key.