I am trying to find pictures which contains a specific word in the file name.
For example any .JPG files that contains "lm" at the beginning or at the middle or at the end of the file name.
A couple of things that might bug you: find won't follow symbolic links by default; find will drill into filesystems you might wish it hadn't (such as a network filesystem or other, in-memory or special, filesystems). You can control all of that from options you will find in your find man page.