A NodeXL manual is in progress. In the meantime, you can get a fair amount of information by hovering your mouse over the column headers in the worksheets and over the buttons in the NodeXL ribbon.
For example, hovering over the "Vertex 1" column header in the Edges worksheet tells you this:
Vertex 1 Name
Enter the name of the edge's first vertex.
To create a NodeXL graph in Excel 2007, enter the graph's edges on this worksheet, one row per edge. The first two columns are required; the other columns can be used to customize the edge's appearance.
To customize the appearance of an individual vertex or add an isolated vertex not connected to an edge, click the "Vertices" tab near Excel's lower-left corner.
After you have entered the edges, click the "Read Workbook" button at the top of the NodeXL graph pane at the right edge of the workbook window. (If the graph pane is hidden, click the "NodeXL" tab
in the Ribbon, and in the "Graph" group, click "Show/Hide Graph Pane.")
The vertex radius determines the size of the vertex in the graph pane. It's used only if you want to set a vertex radius individually. If you leave it blank, a default radius will be used.
Hovering over the Metric column header in the Overall Metrics worksheet tells you this:
This worksheet displays overall metrics for the graph. To have NodeXL calculate the overall metrics, follow these steps:
1. In the Excel Ribbon, click the NodeXL tab.
2. In the "Analysis" group, click the down-arrow to the right of the "Calculate Graph Metrics" button, then click the "Select Graph Metrics" button.
3. In the "Select Graph Metrics" dialog box, click the "Overall Metrics" checkbox, then click OK.
4. In the "Microsoft NodeXL Analysis" group, click the "Calculate Graph Metrics" button.