Block displays will show up on your blocks administration page. Once a block display is created and saved, it can be enabled and positioned in your theme by visiting administer >> site building >> blocks and selecting it from the list. Blocks do not accept arguments from any source; the only way to get arguments to a block is to provide defaults to it, possibly via the PHP Code default setting.

• Edit the argument in question; you may want to override this argument if you have multiple displays using it.
• Change the "Action to take if argument is not present" to "Provide default argument". This will bring up a new box called "Provide default argument options".
• The most common default argument type used for blocks is Node from URL, where it attempts to determine if the URL refers to a node, for example if visiting 'node/1' or 'node/1/edit'. User ID from URL is also very common.
• If you change the default argument type to 'PHP Code' (note: You must have permission to use PHP code on your site) you can enter PHP to define the argument needed. Simply return the argument.