“An unbelievable amount of work went on behind the scenes to make this happen.”
You've organized a professional conference. You're giving an opening speech. You want to thank the people who helped you, so you start by talking about how hard those people worked.
An unbelievable amount of work went on behind the scenes to make this happen.
You can use this phrase to describe a very large amount:
She had an unbelievable amount of credit card debt.
If something is countable, use "an unbelievable number" instead:
There was an unbelievable number of people at the opening.
Every event, performance, and company has activity that the audience or customers don’t see. This activity is very necessary, and a big part of the work that they do. We describe this activity as “behind the scenes".
It was a wonderful wedding, but there was a lot of trouble behind the scenes.
It was really cool to go behind the scenes and see what they do every day.
"Went on" means "happened". We use it like this:
What went on between you two after I left?
"Went on" is for talking about the past. The present tense version is "go on":
Is there anything fun going on downtown this weekend?
You can use this phrase to describe the preparation and organization for a big event.
They needed a lot of donations to make it happen, but it was great.
We need to get started if we want to make this party happen.