Tybee: to find your friend's profile page, click the navigation link that says "Friends" at top right.
There's a search box at top right, just below the navigation section.
Enter your friend's character name and click "enter".
Partial name searches don't work, though maybe they will in the future.
For example, you can find me by searching for "lelu" but "lel" does not work.
To find them in-game:
1. See where they are, by using their profile page or clicking on their name in-game. Their street location is listed there.
2. Find the street on the map, if you don't know where it is. :)