Make sure the IIS rewrite module is installed. and copy paste this web.config in your root folder  :
	
	
	
		Code:
	
	
		<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.webServer>
        <rewrite>
            <rules>
                <rule name="Imported Rule 1" stopProcessing="true">
                    <match url="^.*$" />
                    <conditions logicalGrouping="MatchAny">
                        <add input="{REQUEST_FILENAME}" matchType="IsFile" ignoreCase="false" />
                        <add input="{REQUEST_FILENAME}" matchType="IsDirectory" ignoreCase="false" />
                    </conditions>
                    <action type="None" />
                </rule>
                <rule name="Imported Rule 2" stopProcessing="true">
                    <match url="^(data|js|styles|install)" />
                    <action type="None" />
                </rule>
                <rule name="Imported Rule 3" stopProcessing="true">
                    <match url="^.*$" />
                    <action type="Rewrite" url="index.php" />
                </rule>
            </rules>
        </rewrite>
    </system.webServer>
</configuration>
	 
 
Then turn on the pretty URLs from the xenforo admin panel