Hi and welcome to the Wiggy's way to make a base for a stage.

1st make a rough draft
Now I know this is not the prettiest base but hey but hey, it's a rough draft.


2nd

Make a line with a vanishing point.


3rd

Make a somewhat of a base.


4th

Make all corners point towards the vanishing point.


5th

Make the the thickness of your stage (Tip Use different colors to avoid confusion.)


6th

Now wait a second, shouldn't the box be smaller then the building? Indeed it is, so lets make it smaller.


7th

Now lets delete the extra lines that we no longer need. Gasp! Whats that i see, An error on the jump though platform? INDEED there is, so lets fix it.


8th

Now, this is purposely done because this is a common mistake so don't flame me.
Now we corrected our mistake our stage looks fine.


9th

Ok, then let color everything the same color.


10th

Use fine details Eg. Cricks, cracks, brick details to lighting)
we just finish a sprited stage base

Not quite sure how this is related to flash... moving it to artwork

Actually it's a tut for making a ssf2 stage, its a bit small I know.

[edit]
Wait Flash, flash or Smash Flash?

Flash as in the program flash not the game...