I want to continue MS in Network Security but I think my knowledge about Network Security is not enough.So, what I should I do?

Security is not something you should "have a go" with. there are some basics - like ensuring you have strong passwords and certain ports like port 80 are secured - but it depends on what you require, or what you mean by MS in network Security. If you want to do it yourself looks a CISSP course or what hate courses.