Absolutely nothing yet.
You can leave the Arduino in a drawer, while you download the source file (which you then need to open in a text editor and copy). Then, paste it into the IDE.
Then, create a new tab, with the name of the .h file, and download the header file, open it in a text editor, and copy the contents. Paste them into the new tab.
You can verify the code without even having the Arduino plugged in.
There are a lot of assumptions in that code about the hardware that you have.