This library provides a Timemark abstraction of the classical "Blink-without-delay" pattern. Please see the example sketches for typical usage (button debounce, timeouts, multiple blink, etc).
Download and unzip the Arduino-Timemark library into your sketchbook libraries directory. Rename from Arduino-Timemark-master to Arduino-Timemark.
The Timemark library and examples should be found in the Arduino IDE File>Examples menu.