If I’ve done this correctly, the three files for the blink102 sketch have been attached. If you put all three files into a blink102 directory and double-click on the blink102.ino file, an IDE window should open with tree tabs.
Take a look at the files to satisfy curiosity, change the LED pin in the blink.h file if necessary, and then click on the download button. When the download completes, your on-board LED should blink at 2Hz.
blink102.ino (1.57 KB)
blink.h (1.07 KB)
subs.ino (1.28 KB)