converting .htaccess to web.config

I am intending to limit download links for some users in my Windows Server in which iis is installed in order to being asked for username and password and also want this username and password is extracted from a file with .txt suffix In apache or with the following code in htaccess:

AuthType Basic AuthName "vip user" AuthUserFile "/public_html/vip.txt" require valid-user

I have been doing this before. Please help me and write what should be done in iis. If it is possible the above-mentioned code may change to web.config, please do it for me and I'll be so grateful. Thank you in advance.