There are three ways to do this:

1. You can enter decimal coordinates directly in the search field and choose Go to move the red pin directly there - see example below.
2. On the Locations page, import a KML file containing the Placemarks you need
3. Edit the URL in your browser address bar to set exact coordinates - if you need to generate URLs for TPE from external data sources (e.g. a spreadsheet or a script), this can be a useful technique

Example

The screenshot below shows the coordinates for Mount Whitney in California. The coordinates are parsed and displayed as the top search result. Click GO to move directly there.