Scratch

<when green flag clicked>
<go to x   <pick random(1  )to( 480 )y   <pick random(1  )to( 360

That script will make your sprite appear in a random location every time the green flag is clicked.

Wait....I tried this and well...here is what happens
I am a starfish sprite and i'm trying to collect money(which is the sprite that moves in different places)

My background is scrolling, so how do i collect the money?

ok...look for "money hunt"

I have found an easier method to do scrolling with many sprites . It requires only 2 variables.[blocks]first make a variable <{scroll x}> After that make a variable <{ steps }>
then go to the stage and write in this script <when green flag clicked><forever><if><key[right arrow]pressed?><set{scroll x}to(-3)<wait( 3)secsc> <set{  scroll x}to( 0) and for left arrow do the same thing but change -3 to 3.Then also write<when green flag clicked><forever><if><key[right arrow]pressed?><change{ steps }by(1). Do the same thing for the left arrow but exchange 1 by -1. Then write in if the Green flag pressed Forever If Steps = 30 or >30 then broadcast come on. Then make a sprite and in it  write Forever change x by scroll x. Then type when Green flag pressed hide . Then type When i receive come on go to x 230 and y 100 or wherever you want show and then snap the previous script to it. and then type When green flag clicked forever wait until x < 150 and touching edge
hide. Then go to the stage and type if steps <250 broadcast come again. And in the sprite type If i receive come again go to x-238 and y100 or whatever you want it to be . Now it will not flicker when it comes .thanks. :-)

sorry archmage...I will be sure to mention you 

Go to http://scratch.mit.edu/forums/viewtopic.php?id=2440 for scrolling help.