The Real Issue
But the Find function is already perfectly visible to users. It’s right there with other critical functions like Copy and Paste under… say, where did…?
You’re only scratching the surface of a bigger problem. For reasons not explainable by science, certain browser designers elected to hide the menu bar by default. They apparently felt it would be a lot easier for users to memorize secret keys combinations than to trouble the users with something as standardized and discoverable as the File Edit View menus. That design decision is embedded in a still larger UI trend to reduce discoverability, manifested by favoring icons over words, gestures over visible controls, and arbitrarily coding links.
Replicate Browser Functionality?
As for dealing with your small piece of the issue by adding a Find control to your web page, how would it be implemented? A blank at the top of the page could scroll out of view, which would make it awkward to find the _n_th instance of a string; I think Find-as-you-type would be infeasible. So, now you’re talking about an AJAXy light box or pane that doesn’t scroll, but that would have its own idiosyncratic interactions. Can that be done without confusing users, keeping in mind these are “non-tech” users? Will it throw off tech-experienced users who are expecting something just like Find, but end up with something somewhat different? Will your UI be consistent with my UI if I choose to do the same for my web apps?
This is the problem with replicating browser functionality in the web app: it's difficult to get something that works as well as the browser, and even then, it won't be fully consistent with either the browser or other apps.
I think you might have better results educating users on the browser’s Find functionality, and whatever other functionality users should be using. This has the advantage that once users learn about the functionality from you, they can use it for any app/site, not just yours. If your site/app is used by a specific organization, maybe you can persuade IT to set browsers to display the menu bar by default, and/or show the Find icon in the toolbar (I’d be interested to know if that actually encourages more Finding).
If you’re making a web site where Find is especially useful, maybe try displaying the text “Find on this page = Ctrl-F” at the top of each page, perhaps right under the Search box. Or maybe have a space at the top for “tip of the day” (do those work?), which could also be used to educate users on other hidden browser features like Copy and Bookmarks/Favorites.