How to "Ctrl-F" in iPhone's Safari browser?
I don't have an iPhone anymore, but my memory tells me this:
iPhone
Search using the standard search bar.

The web search suggestions are at the top.
The website search results of the currently viewed website are at the bottom.

iPad
Search using the standard search bar.

The web search suggestions are at the top.
To search the website use the entry box which pops up right above the keyboard.

All of this may change with iOS 6 and Mountain Lion. The WWDC2012 announced that Safari for OSX will integrate a Chrome like omnisearch bar . Most likely we'll see something similar for iOS as well - at least i hope so :).