Use am/is/are going to for a plan you have already decided. After going to, use the base verb. (I'm = I am.)
I'm going to study
I'm going to study tonight.
I'm going to call Amina later.
We're going to eat at the cafe on Moffen Street.
Try it: ___ study tonight. (I'm going to / I going to / I'm go to) Answer: I'm going to — You need am before going to: I'm going to study. (I'm = I am.) Don't drop the am, and don't change "going to".
am, is, or are?
Use am with I, is with he / she / it, and are with you / we / they.
I'm going to help.
Hiroshi is going to visit Senfarren.
They are going to stay.
Not "He are going to come." — say "He is going to come.". Use is with he, she, it, not are.
Try it: Hiroshi ___ visit Senfarren. (is going to / are going to / going to) Answer: is going to — Hiroshi is one person (he), so use is: is going to visit. ("are" is for you, we, they.)
Keep the verb plain
After going to, the verb stays plain. No -s, no -ing.
She is going to study.
He is going to come at six.
They are going to play in the park.
Not "He is going to studies." — say "He is going to study.". After going to, use the base verb: study, not studies.
Try it: She is ___ tonight. (going to study / going to studies / going to studying) Answer: going to study — After going to, the verb stays plain: study. Not "studies" and not "studying".
Don't drop 'to'
Keep the small word to: I'm going to study. Don't leave it out.
I'm going to visit Amina.
We're going to eat soon.
He's going to play later.
Try it: I'm ___ Amina on Saturday. (going to visit / going visit) Answer: going to visit — Keep the small word to: going to visit. Don't drop it ("going visit" is missing the to).
isn't / aren't going to
To say a plan is NOT happening, add not after am/is/are. (isn't = is not; aren't = are not.)
He isn't going to come.
We aren't going to stay.
He is not going to come. = He isn't going to come.
Try it: He ___ come tonight. (isn't going to / not going to / doesn't going to) Answer: isn't going to — Add not after is: isn't going to come. (isn't = is not.) You don't use "doesn't" with going to.
Asking
To ask, put Am / Is / Are first: Are you going to...? Is he going to...?
Are you going to study?
Is he going to come?
What are you going to do?
Try it: ___ study this weekend? (Are you going to / You are going to / Do you going to) Answer: Are you going to — To ask, Are comes first: Are you going to study? "You are going to" tells, it does not ask, and you don't add "do".
Try it: They ___ play in the park. (are going to / is going to / going to) Answer: are going to — "They" goes with are: are going to play. Keep "going to" and the base verb.