Serial Communication - drawing data from the slave to an LED matrix

[mattitup]

I'm working on 1-pixel pacman on a 64x32 LED matrix using an Arduino Mega. I also have a 32x16 LED matrix and an Arduino Uno and would like to use them to continuously draw the player's score to the 32x16 as the game progresses.

I'm new to Arduino so I've been researching about serial communication and I2C but I can't seem to make it work. I started two new sketches with some code I found at lcd - Sending a value from one arduino to another - Arduino Stack Exchange and I'm now able to at least send data from the Mega but I still have a few questions (sorry if they're stupid)

How can I verify that the Uno is receiving the data?

How should this be wired? I have the Uno and Mega connected via TX-RX, RX-TX, and grounded. I have a power source coming to both LED screens and all the necessary pins connected to produced color (hooked up to both screens and their relative processor)

How do I actually run this when its complete? Do I have two sketches open and run the sketch for the pacman game?

Any help would be greatly appreciated. Thank you! (:
Here's an example of the code I'm using to just try and understand how this whole process works:

[Robin2]

You need to post your programs.

Also post an example of the message that you want to send from the Mega to the Uno (hope I have the direction correct).

The Mega has 4 HardwareSerial ports - which one are you using to talk to the Uno (hint, NOT Rx0 and Tx0).

Have a look at the examples in Serial Input Basics - simple reliable ways to receive data.

...R

[mattitup]

I had them on TX0/RX0 but have now moved them to TX1/RX1.

I attached a picture of the programs. I realize now that 300 is an invalid message since it's a number. So I should refer to example 4 in the guide you linked?

[Robin2]

mattitup:
I attached a picture of the programs.

Pictures of text are no help. Just post the code.

To make it easy for people to help you please use the code button </> so your code looks like this and is easy to copy to a text editor. See How to use the Forum

...R