If you want to find specific ongoing threads, a place to start is the "Today's Active Topics" page, as mentioned previously. Looking back over that list, you can see every thread that has been added to for the previous 24 hours or more. To find older threads that you're interested in, check in the particular forum most appropriate for the topic. If you want to find information about a topic not recently discussed, then the search function is what you need.
There are two "Searches" possible here - one for the Forums proper, one for the general Stovebolt site and/or the net. When you use the search switch that is with the Forum "information links" you will be taken to the Forum-exclusive search page. Keeping the search terms short and concise will achieve more relevent results; limiting your search to particular forums will be quicker; searching for posts by a particular user name or number is also useful if you recall who said something about a topic you're interested in, but can't remember where. The search function simply matches the words you specify, even though they may not have been used in a topic that is relevent, so use some thought in your search. For some helpful tips, see this post in the IT Shortbus forum.
To search beyond the Forum, if you can't find any or enough information here, head up to the "Search" on the links row at the very top of the page, the Google search. This is a wider search that allows searching the entire Stovebolt site, or the entire web, and also includes a link to the Forum search shown above. It should return more results, but may contain as many, or more, irrelevent responses. Again, precision in the use of search terms is key. Another good place to check is the Tech Tips, linked from the row at the top of every page.