Variables in a table in HTML email

When I put a table in a HTML email from my ASP.Net using System.Net.Mail, I cannot figure out how to use variables.
Out side of the table, I can use the value of a text box (txtMyNumber.text) or Format(txtMyNumber.Text, ####).  But when I put either in the table, it uses the name of the text box instead of what is in the text box.
Any ideas?  Hopefully a simple answer...
Thanks,
Carthalion
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