Hi Mohammed,
You need to check your IIS, if the Basic authentication service role is installed (it is not installed by default), to install it, you go to Control Panel\Programs and Features then select Turn Windows features on or off. This will open a new dialog
for you, go under the security node and check basic authentication and click ok. Then you need to enable basic authentication for your web service, you go to IIS Manager, select Team Foundation Server and from the right panel select authentication and disable
everything other than basic auth. Then do the same for the tfs node under Team Foundation Server, then restart your IIS. This way basic authentication will be enabled.
Please let me know if that did not work for you.
Thanks
Mireille