Using the Find command will help you do this.
Finding all jpg files within a directory using a wildcard:
find . -type f -iname "*.jpg"
Finding all directories within a directory using a wildcard:
find . -type d -iname "*dir*"
Breakdown of commands:
find . -type f (or d) -iname "*file_or_dir*"
(command) (current directory) (File or directory) (case-insensitive file or directory name; * is the wildcard.)
Another fun command is "tree", which shows you the entire contents of a directory in a more graphical view.