how to get information regarding lecturer vacancies in theses colleges
You didn't mentioned the name of the colleges in which you are doing this enquiry about vacancies. I would request you to be more precise regarding that.
Now in general, you can get such vacancies in the State Public service commission website. So you can look at that (i said this as per West Bengal). For your state it may vary. As you haven't mentioned your state, I can't specify that.
I hope my answer helps. All the very best for your future endeavors!