Hello Rixu and Seema.
I am still not sure I understand what your request is.
If you want to search just the forum, you won't need to go to Google. Just make sure to choose ENTIRE FORUM in your search.
You only have the option to search within a forum, within a board, within a topic, members, and the entire BrillKids site.
You can type in a particular topic, and the forum results will show you what topics or threads have that searched keyword.
If you search ENTIRE SITE, it will use a Google engine. That's the only time when it will use Google.
The search function can be found on the upper right corner of the forum, and looks like what is displayed below: