I have Sony Xperia Tipo. I connected to the WiFi at my college. But even after connecting I am unable to access the internet. What is the problem?
If you college uses Eduroam, there's actually a fairly lengthy process to properly connect. It essentially comes down to the network certificates in use, and obtaining and installing them on your phone. As you have Android, you may benefit from using a 3rd-party app to connect to this network (as that is what I've done). The one I used is here: eduroam CAT , although there are certainly alternatives you may prefer.
If your college does not use eduroam, the requirements will be different. Try connecting to the wifi, and browsing to any commercial website. If your college has a redirect system, you will be redirected to a page where you can login and register your device.
If the browser redirect fails, go to your college's IT page and look for articles showing you how to connect. That will give you the specific information that you need.