正常情况下您只需要将当前目录下的FreeHttp.dll复制到fiddler安装目录Scripts目录即可。
如果您使用的是较老的windows版本（如未升级的window7），那您系统的.net framework 版本可能无法加载freehttp。
这种情况下您可以使用LowVersion文件夹下的FreeHttp.dll。（不过依然建议您直接升级您的.net framework 到4.5或以上版本）
Normally all you need to do is copy the freehttp.dll from the current directory into the Scripts directory of the fiddler installation directory.
If you are using an older version of Windows, such as unupgraded window7, then freehttp may not be loaded by the.net framework version of your system.
In this case, you can use freehttp.dll under the LowVersion folder.(it is still recommended that you upgrade your.net framework directly to version 4.5 or above.)
