FPAlbum

Q: What should I do to make the directories conf and data writable by the album?

There are many possible ways.
If you are using Windows, make sure the directories and all files inside them are NOT read only.
If you are using UNIX or Linux, make sure the directories and all files inside them are writable and executable by all users. In most cases, a command

chmod 777 data conf

will do the job.

Q: How do I install the WordPress plugin?

When you got the php file, put it into wordpress's plugin directory (wp-content/plugins). Enter the admin page and activate the plugin in the Plugins menu.
You can then go to the Options menu and change the setting of the plugin if you want.