Not sure if you are trolling? But, anyways.
Levels are called "Layouts" in Construct. They are used to build up levels/menus/etc in your game. Then used to add objects, platforms(depending on game type), collisions, enemies, etc. Then the "Event Sheets" are used to control the actions the objects in the game have, and how they interact with one another.
If your question is legitimate, I would definitely load up some of the examples in Construct, reverse engineer them. And, especially check out some of the resources on the website here(under the "Learn" section). Follow along with some of the tutorials, and read the documentation if you get stuck on certain things. There are a ton of tutorials elsewhere as well, check YouTube ;)
All the Best, and good luck with your projects.