You should be able to to echo out a phpinfo(); on a page in that directory to scope this directory out.
That is what the contents of the .htpasswd file should look like. One username and password per line, separated by a colon. Notice the password is encrypted though. You will need to use a special tool to encrypt your password in this way (MD5). David Walsh has a tool just for this.
In fact, I obviously first learned this from David as pretty much this exact same tip is on his site. Still, I think it's worthy of re-posting because this is an extremely useful tool to have in your toolbox.