passing user information from php to django
You must use one of these possibilities:

Your friend gives you direct access (even only read access) to his database and you represent everything as Django models or use raw SQL. The problem with that approach is that you have a very high-coupling between the two systems. If he changes his table or scheme structure for some reason you will also have to be notified and change stuff on your end. Which is a real headache. 
Your friend provides an API end-point from his system that you can access. This protocol can be simple GET requests to retrieve information that return JSON or any other format that suites you both. That's the simplest and best approach for the long run.
You can "fetch" content directly from his site, that returns raw HTML for every request, and then you can scrape the response you receive. That's also a headache in case he changes his site structure, and you'll need to be aware of that.
I am building a web app in django and I want to integrate it with the php web app that my friend has build.
Php web app is like forum where students can ask question to the teachers. For this they have to log in. 
And I am making a app in django that displays a list of colleges and every college has information about teachers like the workshop/classes timing of the teachers. In my django app colleges can make their account and provide information about workshop/classes of the teachers. 
Now what I want is the student that are registered to php web app can book for the workshop/classes provided by colleges in django app and colleges can see which students and how many students have booked for the workshop/classes. 
Here how can I get information of students from php web app to django so that colleges can see which students have booked for workshop. Students cannot book for workshop untill they are logged in to php web app. 
Please give me any idea about this.. How can I make this possible