The How-tos section contains useful guides how to use specific functionality within Umbraco.
Quick Tips
How to show the Trace window
Append umbShowDebugTrace=true to the URL as a query string parameter like so:
http://localhost/my-page.aspx?umbShowDebugTrace=true
How to find the problem of a non-rendering .NET Macro
Navigate to the Umbraco backend (/umbraco/) and then locate the macro (Developer -> Macros -> Macro Name).
Click on the Browse Properties button, this popup window will show the stack trace which is causing the error.