In the top right of the screen, you'll find the search bar. It's there on every page of the system. From here, you can search for goals or people. Search results will cover the entire organization, not just your own goals (excluding private goals you cannot see).
The search engine will give results in real-time as you type, so just keep typing a few more characters if you don't see the result you're looking for, or if you're seeing too many results to list.