Dear aspirant, 

Software engineering is an application in developing of a software with different methods. It is a subject in Computer Science Engineering and Information Technology Engineering . If you  learn software  engineering  , then you can become a software developer. As you may know that engineering from good colleges will ultimately lead to a good placement in a company. It doesn't matter if you got 51 % in 12th std , it is done ,you cant change that. So your next step is to get good marks in engineering entrance exams like JEE mains and MHT-CET . Colleges give admissions on the basics of your 12th std PCM marks and entrance exam marks . The admissions are on the merit basis, so different colleges have different criteria . But don't get into a dilemma that you wont get a admission and study that subject, you can get admission in an engineering college , it depends on seat availability . 

Here are the colleges that i prefer you can get as i consider you must have done well in entrance exams :

1) Savitribai Phule Engineering College Pune.

2) Sinhgad College of Engineering 

3) Pune institute of Computer Technology

4) AISSMS College of Engineering Pune

5) MIT school of Engineering Pune

6) Dhole Patil College of Engineering Pune 

7) MKSS'S Cummins College of Engineering for women Pune 

8) DR DY PATIL School of Engineering 

9) Imperial College of engineering 

10) Modern Education Society's college of engineering