IR Code Grabber
Most IR remotes today use the NEC standard. It looks like this.
One of the advantages of using Arduino is that you do not have to actually build many projects. Just upload a program and plug in a few components.
To capture these code you need one of these. VS1838B or equivalent. Connect 5 volts and ground. The signal line goes to the pin you have designated in the program.
Activate the seial monitor and set it to 9600 baud. Now upload and run the program. Any remote using the NEC protocol (most of them today) will have its 4 byte code show up (in hexidecimal) on the monitor window.