A television drama is broken into four acts, a teaser and a tag. A teaser is a quick opening that sets up the action and is intended to engage the audience. The four acts within the script move the story along. The end of each act should be a cliffhanger. A cliffhanger introduces a plot twist -- such as a new piece of information -- that's designed to hold the audience's interest through the commercial break. A tag is a quick scene at the end of the show that either sets up the next episode or wraps up a plotline within the episode. A television comedy follows a similar structure, but only has two acts instead of four.
When writing a television script, you must have scene headings which indicate where the action is taking place, what time of day it is and whether or not the scene takes place inside or outside. These scene headings -- also known as sluglines -- must be written in a certain way. For example, if the scene takes place inside a diner at night, the scene heading would read as such: INT. DINER - NIGHT. All letters within the scene heading must be capitalized. "INT" stands for interior. "EXT" stands for exterior.
Underneath each scene heading -- separated by a space -- is the action block. The action block describes the most crucial elements transpiring within the scene such as the characters involved and what they might be doing. Action blocks are spread throughout the script and describe any event that takes place. These blocks of action should be as minimal as possible and not too wordy. If the writer of the script is also directing the show, she may include camera movements such as pull back and zoom in. However, if the writer is not directing, camera movements should not be included. An example of an action block would read as follows: "Joe sits at the diner counter and sips coffee. Next to him sits Max. The diner is half-full. A jukebox plays a rock tune."
If a character is introduced for the first time within an action block, their name should be written with all capital letters. A brief description should be given, including their age and dress style. Their age should be written next to their name in a parenthetical. The character's name is written in the middle of the page once they start talking. Directly underneath their name -- two inches from the right margin and one inch from the left margin -- is where you write the character dialogue. If need be, you can describe how a line is meant to be read underneath the character name using a parenthetical. For example, if a line is meant to be sarcastic, you would write (sarcastic) between the character name and the dialogue.