Issue with word doc generated through code

Hello,
          I have created word doc through code in my asp.net application.  Using the following code i have done this
StringBuilder strHTMLContent = new StringBuilder();
strHTMLContent.Append("<html><body>".ToString());
strHTMLContent.Append("<br>".ToString()); strHTMLContent.Append(
"<table align='Center'>".ToString());

// Row with Column headers
strHTMLContent.Append("<tr>".ToString()); strHTMLContent.Append(
"<td style='width:100px; background:
# 99CC00'><b>Column
1 < / b > < / td >".ToString());

strHTMLContent.Append("<td style='width:100px;background:
# 99CC00'><b>Column
2 < / b > < / td >".ToString());

strHTMLContent.Append("<tdstyle= ...