This being a technical forum, lots of folks want to post code in their messages. vBulletin has a special tag for this: [code]. You can embed code inside this tag to ensure it looks like code when viewed and that it retains it's formatting (particularly leading spaces for block indentations).
Example (no code tags):
Function Foo Returns Boolean
Boolean bVoid
Function_Return bVoid
End_Function
Example (with code tags):
Code:
Function Foo Returns Boolean
Boolean bVoid
Function_Return bVoid
End_Function
The easiest way to add the correct tags around your code is to select it and then click on the # button in the editor to wrap the tags around the selected text.

Note: The # button is not available in the Quick Reply editor, you have to use the Advanced editor. Click the Go Advanced button a the bottom of the Quick Reply editor to switch editors.