Hii

For admissin to BSc Nursig courses, different colleges conduct there own entrance examinations.
BSc Nursing is a four year course offered under tha medicine branch. To be eligible to get admission into this course, you need to qualify class 12th exam with physics, chemistry and biology and score a minimum 50% in the examination.
The following are the top colleges for BSc nursing along with there entrance exams.
AIIMS - Bsc nursing admission test 
AFMCE Pune - AFMC BSc nursing entrance exam
Nitte University Mangalore - NUPMET
Banaras Hindu University - Bsc ( nursing) Admission test
CMC ludhiana - Entrance test for admission to Bsc nusing
GGSIPU - IPU CET
Also there are some state leel entrances also like MHT CET. 

You can visit the official website of the colleges to fill in the application forms for the admissions.
Also if you wish to know about any particular college in detail, you can mention the name of the college so that i can provide you the specific information.

Hope this helps
Thanks!