public class CalendarGenerator
    {
        private int year;
        private int month;
 
       
        /// <summary>
        /// Build the report with WordTemplate
        /// </summary>
        public void GenerateDocument()
        {
            //Set the year and month to the current year and month
            DateTime today = DateTime.Now;
            year = today.Year; 
            month = today.Month;
           
            // Form the name array that will be passed to WordWriter.  The elements
            // of this array are the names of the merge fields in the calendar document
           
            string[] arrNames = {"Block1", "Block2", "Block3", "Block4", "Block5", "Block6",
                                    "Block7", "Block8", "Block9", "Block10", "Block11", "Block12",
                                    "Block13", "Block14", "Block15", "Block16", "Block17", "Block18",
                                    "Block19", "Block20", "Block21", "Block22", "Block23", "Block24",
                                    "Block25", "Block26", "Block27", "Block28", "Block29", "Block30",
                                    "Block31", "Block32", "Block33", "Block34", "Block35", "Block36",
                                    "Block37", "Block38", "Block39", "Block40", "Block41", "Block42", "MonthYear"};
           
            // Determine on which day of the week the month begins
            DateTime thisDate = new DateTime(year, month, 1);
            DayOfWeek startday = thisDate.DayOfWeek;
 
            // Get the number of days in the selected month
            int daysinmonth = DateTime.DaysInMonth(year, month);
 
            //Declare the object array that will be used to hold the
            // values inserted into the calendar template
            
            object[] arrDayBlocks = new object[43];
                     
            // The first date of the month is, as always, 1
            int dayofmonth = 1;
 
            // Loop through all of the available blocks in the calendar             
            for(int iDayBlock = 0; iDayBlock <= 41; iDayBlock++)
            {
                // If the block exists before the first day of the month, enter an empty string
                if((iDayBlock < (int)startday) || (dayofmonth > daysinmonth))
                    arrDayBlocks[iDayBlock] = String.Empty;
                else
                {
                    // Otherwise, it's a valid block, so enter the day of the month
                    arrDayBlocks[iDayBlock] = dayofmonth;
                    dayofmonth++;
                }
            }
             
            // The last element of the value array is reserved for a DateTime struct.
             // Using MergeField date formatting codes, the template merge fields will
             // display the Month name and 4-digit year in the appropriate places
            
            arrDayBlocks[42] = thisDate;
           
            // Instantiate a WordTemplate object
            WordTemplate wt = new WordTemplate();
           
            // Open the template file
            string templatePath = @"..\..\WordTemplateFiles\CalendarTemplate.docx";
            wt.Open(templatePath);
           
            // Set the datasource with the name and value arrays defined above
            wt.SetDataSource(arrDayBlocks, arrNames);
           
            // Process the template
            wt.Process();
           
            // Save the document to the desired location
            string docName = String.Format("Calendar-{0}-{1}_output.docx", this.month, this.year);
            wt.Save(@"..\..\WordOutputFiles\"+docName);
        }     
    }

 Template: CalendarTemplate.docx

Output: Calendar-7-2013_output.docx