Start off with your choice if base color, and let it dry completely.
Add a dab of your second color polish somewhere.
Grab your Saran wrap. I just bunch it up and you will get a close up of how my Saran wrap looks once dipped in polish.
Here's what mine looked like, yours might look different which is absolutely fine.
Dab in your nail.
Here's the look I got
Add a top coat
Here's a video, kinda hard doing it with one hand, but you get the idea :)
Here they are after the top coat