We have added a site search option in the sidebar. See it at the bottom of the screen grab at left.
You can use this search to do site searches.
Because of the way SquareSpace have set this up mostly for mobile phones it does not look that nice on a PC but it works.
Following the last post from Christine I did a search for "car wash" on our site and it found my posting about girls wearing high heels when they wash cars.
Click on the following picture if you would like to check out that posting now.