How to fade in?

How would I set the screen to black when a player joins my game, then have it fade into regular view?

for i =1,10 do 
wait(.05) 
a = 10-i b - a*.01 
text.TextTransparency = b 
end -- try that

It iteraes thru and subtraces 10-the number the iteration is on then divides it by .01 to get a 1/10 which is basic transparency.