When you configure HotSpot, the hotspot service is running on port 80 (which was used by winbox to check for versions, download plugins before setting up hotspot). The hotspot setup changes the "www" port to something else. You can find out the current port for the "www" settings with "/ip service print". Then just add this port to your routers' address in you WinBox connect dialog. E.g. if the new port is 8080, type "192.168.1.1:8080" to connect to your router at ip 192.168.1.1.
The default service port for winbox after you setup the hotspot is :8081
Note, to get to winbox from inside the network (the network which the hotspot is serving) you have to login to the hotspot service before you can connect to the router via winbox. But again, you need to connect using port 8081 after you log in.
Yes as jarosoup said you have to log into the hot spot first. That is access IE or what ever browser that you use, it will bring the log in for the hotspot and provide the necessary credentials and you are in.