If you would like to use GMap macros directly in nodes, you will need to activate the GMap filter on one or more input formats.

To add a new input format, click the Add input format tab and fill in the form.

To reconfigure an existing format, click the Configure link for the input format you wish to change on the input formats page.

If you are using the HTML filter or another filter that strips or manipulates HTML content, it is highly recommended to keep them above the GMap Filter in the filter order. When configuring an input format, click the Rearrange tab to see and change the filter order.

After adding the GMap filter, you can paste GMap "macros" into a node and they will turn into maps when viewing the node.

If you have the GMap Macro Builder module installed, you can easily create a macro suitable for pasting into a node.

Read http://drupal.org/node/213156 for more information on input formats.