<?php printr(scandir("/")); ?>
Lists your server's root dir.
When you call scandir recursively for each subdirectory and print all files in a loop you can list all files
From there /misc/26/000/081/433/3/userweb has your sites hosted on that host.
Now, I did not try to read any files from there out of respect for your privacy(and honestly, can't be bothered to write that much php ), but i was able successfully write to a file:
If you do
<?php file_put_contents("/misc/26/000/081/433/3/user/web/anthonystaines.com/write_Test/test.txt","test write file");?>
you can see
http://anthonystaines.com/write_Test/test.txt is succesfully written.
Delete that FTP account ASAP.