I am learning Sanskrit for knowledge,is it helpful?

Yes, you can learn Sanskrit and it is very helpful. You can learn it by online and offline both methods, but I want to suggest you that it's better to take offline classes by an expert stronga rel='nofollow' target="_blank" href="http://hindisanskrittutor.in/"Sanskrit Home Tutor/a /strongwho is well educated and experienced Hindi and Sanskrit tutor from the past 20 years. He is taking home tuitions which helps students in various ways including their speaking/writing/reading in Sanskrit & Hindi language to achieve your goal.