Hi! I would recommend to check out this guide: GUIDES | Dara Amarie (dara-amarie.com)
It’s a fantastic guide on overlays 
Other helpful/bonus guides: HOW TO: Use Easing Functions 
- Creator’s Corner / Directing Help & Tips - Episode Forums (episodeinteractive.com) (to spice up your overlay) as well as layers: HOW TO: Move Characters / Overlays to the Layers - Creator’s Corner / Directing Help & Tips - Episode Forums (episodeinteractive.com)
Understanding layers is important!
Here’s an example code:
EXT. CITY GARDEN - DAY with COFFEE SPILLL A1 to 0.136 6 224 in zone 1 at layer 10
&zoom reset
&speechbubble reset
@BELLA left
@BELLA moves to layer 9
BELLA (talk_angry)
Ouch, I’m used to attracting hot people, but not hot things.
@ANGEL right
&overlay COFFEE SPILLL A1 opacity 0 in 0
ANGEL (talk_pointup_pretentious)
I’ll get a napkin.
@BELLA left
@BELLA moves to layer 9
&overlay COFFEE SPILLL A1 opacity 1 in 0
BELLA (talk_angry)
Make that a handful of napkins.
Breaking down this code:
EXT. CITY GARDEN - DAY with COFFEE SPILLL A1 to 0.136 6 224 in zone 1 at layer 10
Firstly, I positioned the overlay by moving it around the screen (I always place my overlays into the scene with the scale 1.000 and the x y value of 0 0). Then from there, I make changes to the code (since the previewer tells us the coordinates + zone number, we’d just copy those into our script).
The first number is the scale (size) of it, the second number 6, is it’s x-value (the second number goes from side to side, so from the left to right or right to left direction) the third number 224 would be on the y-axis (from top to bottom or bottom to top), basically think of it like a graph. The second number controls side to side, third number, up/down. First number is size. You can play around with the coordinates, like I’ve mentioned. You can also place it in your scene like this (the second way to have it show up in your scene, using the create + opacity command):
&overlay COFFEE SPILLL A1 create
&overlay COFFEE SPILLL A1 scales to to 0.136 0.136 in zone 1 in 0
&overlay COFFEE SPILLL A1 shifts to 6 224 in zone 1 in 0
&overlay COFFEE SPILLL A1 to layer 10
&overlay COFFEE SPILLL A1 opacity 1 in 0
writing “in zone 1” is optional as it’s the default zone. It will be in zone 1, if no zone specified. in the example above, I used the create command and then I used the opacity command to make it visible (opacity goes from 0 (not visible at all) to 1 (fully visible). For example, 0.5 is kinda see through.
Anyways, in the above example, I placed it next to the background name, rather than use the create command. While the opacity command is required when you use the create command to make the overlay visible, when you place it next to the background name, the opacity command isn’t needed since it should be fully visible. but if you do something like this:
EXT. CITY GARDEN - DAY with COFFEE SPILLL A1 to 0.136 6 224 in zone 1 at layer 10
&overlay COFFEE SPILLL A1 opacity 0 in 0
Your overlay will not be visible. since you set the opacity to 0, after putting it next to the background name.
Anyways, in the example scene above, every time, BELLA, the girl with the coffee stain comes on screen, she’s at a lower layer than the coffee overlay, so it will be in front of her. Also, every time, ANGEL, the other girl, with no coffee stain comes on, I make the overlay go invisible, so it doesn’t show up on screen. However, keep in mind that when you enter a new scene (a new background) all overlays from your scene get cleared!
