how do I search this form, only see new topic button
Not sure about other tech products (phones or ipads) but if you're on a computer there is a large shaded box at the top of the forum page. Just type in what you want to search for and then select Travel Forum when your results come up. This allows you to choose how recent you want the results to be.
What browser on what device are you using to view the Forum? Different devices display differently.
In addition to the Search box (which is indeed hard to find, as it hides in plain sight on the top center of the page - at least on Firefox on a desktop PC), you can use Google Advanced Search, which I find easier. Put your search term into Google (such as "vegetarian Paris" without the quotation marks). You will get an avalanche of links. Then, on the right near the top, click the gear symbol and select "Advanced Search." Under Sight or Domain, you can put ricksteves.com (for the whole sight) or community.ricksteves.com (for just the Forums).
By the way, this is how I find my old posts - I put "Harold" and the subject in the search bar and limit it to ricksteves.com, and voila!