If "you" are not peoples, just specfic people, we jsut "보고싶어" or "보고싶다". We usually don't use "나는" "너를" in one-to-one conversation.

나는 /너를/ 보고 싶어(요) --- Wow! Great job! When you want to say "want to V", you use "~고 싶다". As for the middle part "너를 (?너는?)", you would definitely be using "를", as "you" is the object of the sentence. However, pronouns in Korean are often omitted. So you can just say 보고 싶어(요). I suggest practicing making more sentences using "고 싶다". Then we can correct and comment on them :)

보고싶어요...should be enough