First of all you must read and learn.
There is a million examples on the internet , but you need to choose your target group.
You need to know who you’re writing it for ,how that person thinks ,what that person needs.
1.Write a strong headline that works.
2.Show your product
3.Explain why is it a good deal
4.Explain why should they buy it now, rather than later
Take yoo time, writing great ads takes time and energy,but you will be rewarded