@manabi do you really think that poster can understand your sentence when he can barely form one? (sarsasm)
@nhoctu97
his friends maybe not really good friend if they don't do anything know that he forever stuck in elementary school
At this point it's akin to the way my ancestors talked in the cotton fields. It doesn't look good on your part, but the good thing is that you're already getting your point across. Yet unfortunately this sentence would get a failing grade in elementary school.
I'm no teacher and my ESL in Japanese is 5th grade at best, but I can at least help you correct the core parts assuming you're a second language learner too...if you feel the need to improve. Otherwise you can ignore this.
his friends maybe not really good friends if they don't do anything knowing that he is forever stuck in elementary school
There's more you could fix but just two mistakes corrected already bumps this up from headache-inducing to just head-scratching. The trailing "ing" is really essential in English so you should get used to it quickly!
This would be like leaving out a "ている" from the end of a word or the entire particle "は" from a sentence in Japanese. Different readers have different skills with context clues so your simple attempt at expressing ideas could become "Results May Vary". You are almost there though. : )