AuthType Basic
AuthName "Auth Required"
AuthUserFile /path/to/.htpasswd
Require valid-user

Now adding the following below this will allow you to exclude directories and files

# Allow access to excluded diretories
SetEnvIf Request_URI "path/to/excluded/directory/" allow
SetEnvIf Request_URI "path/to/excluded/file"  allow
Order allow,deny
Allow from env=allow
Satisfy any