// Get the first table of the Word Document
Word.Table firstTable = this.Tables[1];

// Loop over the rows in the table
foreach (Word.Row row in firstTable.Rows) {
   List<string> cellValues = new List<string>();
   foreach (Word.Cell cell in row.Cells) {
      string cellContents = cell.Range.Text;
      // Now cellContents has the text of the current cell...
   }
}