I am searching for a sibbling who was possibly adopted or put into the foster care system almost 21 years ago. Is there anywhere I can go or anything I can do to find him.

You can post your information on reunion sites, but that's about it.

Since you have no legal/real connection to the case, you have no rights to the (sealed?) information.

Your parent that placed the child for adoption would have to be the one to start a search with the county/state or with the adoption agency, not you.

Since you make no reference to the your siblings birth mother I assume you have no contact with her. Synnen has given you very good advice. All I can add is active searches begin with as much information as you can get. If you know a close friend or relative of the birth mother they may remember some information that may help you. In searches like this I remind fellow searchers, be honest, be sincere, be sensitive to the feelings of all involved,