First, thank you for your questions. I commend your desire to improve. I will correct your questions: How do I learn to speak English fluently? and How do I use my vocabularly correctly in a sentence?
The answer to your first question is practice, practice, practice. Speak Engliah at every opportunity that you get. Make a robust plan for learning: In addition to your tutoring, you could get a language partner, there are many videos on Youtube for learning English, when you encounter English, say even printed on the back of a box of breakfast cereal (!), read it out loud to practice your pronunciation, watch music or TV show videos with closed captions and try to say the words as they are printed.
As for vocabulary, in order to use it correctly make sure that you know what part of speech it is. Is it a verb? An adjective? An adverb? etc. I make flash cards to learn my vocabulary in Spanish. I carry some everywhere I go so even when I am waiting in line at the grocery store, I can be studying my vocabulary. Another way to make certain that you are using it correctly is to try substituting a synonym in the same sentence. If the synonym makes sense there, your vocabulary word will too.
Lastly, keep doing what you are doing, ask questions. :-)