That would depend on your game. What do you consider a level? The most basic way is that each level in your game is a new layout. Each layout has it's own objects, and construct has events to go to another layout. So you can have an event for beating the level, which then loads the next one.
I highly recomend reading the manual and going through the tutorials section. And yes, it has been asked many times. The search boxes on the site will work wonders for finding the answers to commonly asked questions.