how to update SSIS Variable programmatically?

Hi,

  I want to update 2 variables inside the SSIS Package 2008 R2 using asp.net.  this article: http://msdn.microsoft.com/en-us/library/microsoft.sqlserver.dts.runtime.dtscontainer.variables.aspx teaches how to create the variable but i want to update it not create it. is there any easy way to do that?

thank you