Unix-type "locate" on Windows?

You should be able to do what you need to do with dir:

dir [filename] /s

Replace [filename] with the filename you're looking for, you should be able to use wildcards. /s makes it search sub-directories so if you need to you can start in the root of C: and have it check the entire drive.

Nobody talks about "where" command? it search executable file in PATH of current environment.

where <executable>

c:\ where
The syntax of this command is:

WHERE [/R dir] [/Q] [/F] [/T] pattern...

Description:
    Displays the location of files that match the search pattern.
    By default, the search is done along the current directory and
    in the paths specified by the PATH environment variable.

Windos has the most straightforward answer. But if you're fond of the command line, you may want to look at powershell too. To accomplish the same type of search you'd use

get-childitem [starting path eg c:\users\] -filter [wildcarded search or filename] -recurse

Which has the nice side benefit of being able to be pumped into a handy foreach statement and run a process against the search results.

get-childitem [starting path eg c:\users\] -filter [wildcarded search or filename] -recurse |
    foreach ($_){
          [do something to $_.fullname , like maybe display my image file or relocate it etc..]
    }