Hello Tamzid. Having a desire to improve your English and fluency is inspiring. There are different ways to go about this which I will name a few:
1. You have to be constant and consistent in learning and speaking new worda
2. Repeat what you hear native speakers say
3. Do more of conversation
I hope I was able to help in one way or the other.
You can check out my Tutor page, I will be delighted to take you through some conversation practice lessons.
Do have a great day :-)