What to do first:
Check the error log /logs/error.log
This will give you an idea as to where your code is going wrong.
If you are writing your own code and are not using a program that supports syntax highlighting then you should download a program like notepad++ (Free). If you have a little money to spend then investing in a program like Adobe Dreamweaver may be for you.
If you are using Google Chrome (free) as a web browser then you can right click the page and click on “inspect element”. Another debugging tool is Firebug (http://getfirebug.com/). This allows you to inspect your web pages for issues.
If all else fails we can provide some limited support or advice on your issue.