The easiest way to find a contact in Skype for Mac OS X is to use the Search field in the upper right of the Skype window.
Simply start typing your contact’s name into the Search field and you’ll see the matching contacts under Conversations. Click the contact you were looking for to open the conversation window.
If you’re using the Search field to find a contact in your Mac’s Address Book, you’ll see all phone numbers associated with that contact next to their name.
You can also use the Search field to find keywords or topics in your chat history.