Save an XSLT to File

I created an XSLT code and would like to save it to a file. Basically each time the application loads the XSLT will overwrite the saved data in the file. How do I save or update an XSLT file with new content?
Codes
var XSLTStr = new StringBuilder(); XSLTStr.AppendLine("<?xml version='1.0'?>"); XSLTStr.AppendLine("<xsl:stylesheet version='1.0' xmlns:xsl='http://www.w3.org/1999/XSL/Transform'>"); XSLTStr.AppendLine("<xsl:template match='/'>"); XSLTStr.AppendLine("</xsl:template>"); XSLTSt ...