Scriptwriting software, such as Final Draft or the free alternative Celtx offers industry-standard script layout templates.
The pros and cons of this type of software are discussed elswhere in depth. If you want your script to look exactly like every other offering, this is probably the way to go. For some reason, it appears that Hollywood studios want all scripts to look as if they were typed on an Imperial sit-up-and-beg typewriter in 1934.
If, however, you want more flexibility, and prefer to generate your scripts in a regular word processor, this is how to do it.
TV layouts vary. Each Broadcaster and Studio has a preferred 'house style'. It's not desperately important you know which style goes where: a good script is by far the most important consideration. The production team can re-format your script to fit requirements, if it makes its way as far as the production process. It's a good idea, though, to submit a script that looks professional. I remember this being one of the more daunting elements of scriptwriting when I started out. The truth is, there's not a lot to it – a few simple rules, is all – and purpose-written scripting software makes it a doddle.
Here are those rules:
In a TV script, the character names appear above their dialogue. They can be underlined, bold or simply uppercase.
Stage Directions must be distinguished from dialogue. Commonly, they are laid out with different margins. They can be italicised or uppercased, but this tends to make them more difficult to read, or, equally disturbing, easier to skip. It's acceptable to draw attention to extremely important stage directions by setting them in UPPERCASE or bold.
There has to be space on at least one side of the script for the director to put camera directions.
It helps the production team if you use UPPERCASE in the stage directions for your characters, so that wardrobe and make up etc. can see exactly who's appearing in a specific scene, and so have plenty of time to prepare the actors, wake them up or drag them out of rehab.
Scene headings should include, in this order: INT for interior or EXT for exterior, the name of the set or location and finally the time of day, usually DAY or NIGHT, but you can be more specific if the script requires it. LATER is acceptable, so is 10:30 A.M or CONTINUOUS. In a production script, each scene will be numbered. There's no real need to number the scenes for a submission script, except to let everyone see how many scenes there are. All purpose-designed scripting software can add scene numbers with a couple of clicks at the end of the writing process. If you know your way around the word processor you're using – and I can't emphasise enough how important it is for you to master it – it should be almost as straightforward to do the same.