Here's a little tutorial I wrote on using the forum Search function. You might find it helpful!
To perform a search, click on the Search link to load the search page. Select which forums you want to include in your search (use the Ctrl key to select multiple forums), and specify the keywords for your search. To make your search more effective, use the following tips:
Use +keyword for required keywords. (For example, specify +new +hut to see posts containing BOTH of those words somewhere in the post.)
Use -keyword to exclude posts with a keyword. (For example, specify -magic to eliminate all posts containing the word ‘magic’ from your results list.)
Use quotes around a phrase to search for a phrase. Use spaces around the word to match the exact word. Example " word " (For example, specify "new hut" to see posts containing the exact phrase ‘new hut’)
You may also specify a specific user’s posts to search for, as well as choose a date range for your search. If you want to see part of the post displayed in the results list, check the box labeled "Show a preview of post body with results."