Configure sub-domain Wordpress on Apache Windows Server

I have a website and a sub-domain for blog on wordpress which need Apache server/ php. All required installations are there and wordpress is running on server, but I am unable to configure the sub-domain for the wordpress. Need help with that. IIS server is also running the main website and other sub-domain, so need a different port like 81. Any expert who can just help me configure this on Apache (along with SSL certificate).