How do you frame a combat scene?
In general, I don't need to; it grows naturally out of the preceding scenes and choices.
When you are initiating the scene without benefit of previous scenes' context, I recommend starting as late as possible. Don't begin with a monologue describing the last hour they've spent investigating the club's White Court connections, begin with the moment the dancers become suddenly aggressive and the PCs are caught in the spotlights. Right as the fight starts in other words.
My question was how should I create a combat scene. Like A-team vs B-team, simple. The thing is that for some reason I cant come up with a convincing combat sequence. The aspects for example, how do I choose them?. Give me an example of a combat scene.
Don't get hung up on creating poetic sounding aspects, just consider anything which may affect the outcome an aspect. Is it dark? Crowded? Overwhelmed by loud music? Or is it a well lit city street lined with parked cars? Your scene aspects are the pieces you (or your players) think are important pieces of the description.