Czar,

I commend you for working on your thesis and for selecting the topic of Assessment of English Language Programs.

In order to develop a well-written and researched thesis, you are going to to have to conduct and obtain documentation/records of the English Language program from the school you use. This documentation can be in the form of test results for students, assignment results, or assessment results from original placement exams given when the students enter into the program.
The documentation can and should be obtained from the teachers who are in your school.
Once you have this documentation, then you will need to analyze it and see what, if any patterns occur on a regular and continuing basis.
Then, you will be able to develop your conclusions for your findings based on the evidence you have obtained.