buloletin board not working after cgi upgrade

[#1]

http://ccgi.topcateng.plus.com/cgi-bin/ikonboard.cgi ;
I'm getting error 500, server errors trying to access my bulletin board
Uses Ikonboard which I think was written in Perl
David

[#2]

Hi David,
Have a read of this and check what you have in your .htaccess files.

[#3]

OK Guy's I'm struggling with this.  As a U*nx /PHP/Perl numpty I need help
I've  checked the permissions of my my files and reduced them where indicated to 750 or below  but it has not fixed the problem.
Where do I find, and how do I access the .htaccess files.  Once there what should I find in them?  What should be in there ideally in the new environment?
Thanks
David.

[#4]

Because Unix regards files whose names begin with a dot as hidden, your FTP client might not show them unless told to. For example in FileZilla one has to select Force showing hidden files on the server menu. You are likely to find such a file in your HTTP root directory (/) but one could reside in any directory to control that directory.
Windows does not handle such files gracefully if they are downloaded to (or created on) a Windows PC. The usual approach is to call them htaccess.txt on Windows, upload them like that then use your FTP client to rename them to .htaccess in situ.

[#5]

Thanks Spraxyt and Bob for your help. Simple when you now how 
Did as you indicated and downloaded .htaccess as a .txt file.  Inside it contained only one line  "DirectoryIndex ikonboard.cgi index.html"  unless there were some non printable characters in it as well.  However, I renamed the file htaccess.txt on the site to disable it and the board now runs OK as far as I can tell. 
So Ive got to working but I'm  no nearer understanding what  the .htaccess file does, why it was there in the first place if the board will run without it? 
Thanks again
David. 

[#6]

Glad to hear it's working again David.
DirectoryIndex is used to define the name of the index file that's used when browsing to a directory (normally index.html, index.php etc,). If your site works without this directive then you've nothing to worry about.