Your script should be between 15 to 25 pages long, or 15 minutes running time. It should be double spaced, but I did 1.5 because double looks ridiculous. Should kind of look like this ...
CHARACTER: <------- With a space between the name and dialogue. I just did about 1.5cm tab space between them...
Stage directions should be in italics but CHARACTER names shouldn't be.
I think the Italics worked properly...
Also, your first page should be character list with a brief description, any props/costumes/set design etc... lighting or anything like that...
Hope that helps