Read about using be going to and the present continuous for future plans and arrangements. Then when you are ready, try these practice exercises.
Making plans for the future
If you have already decided to do something, it is a plan:
I've decided to watch a film tonight.
There are two main types of plan: general intentions (we have thought about it, but don't know when it will happen), or arrangements (we have decided when, where, who with and all the other details).
For general plans, we use am/is/are + going to + verb:
I'm going to get married one day.
For arrangements, we can use the present continuous or be going to.
I'm getting married next month.
I'm going to get married next month.
If you don't know if something is a general plan or an arrangement, use be going to - it's usually correct.
How to use be going to
She's going to start a band.
She isn't going to start a band.
Is she going to start a band?
In spoken English 'going to' usually becomes 'gonna' - you'll see it a lot in song lyrics or film subtitles. However in written English, 'gonna' is really informal so be very careful with this in your writing. It's probably best to avoid using it or just use it when writing to very close friends.
If you can't remember how to make the present continuous, look at this lesson here. We can also use language like "I've decided to", "I've arranged to", "I'm planning to" to talk about our plans. For more information, look at the previous lesson, future verbs.
When you are ready, try these practice exercises to test yourself on be going to and the present continuous.