One of the easiest ways to track your time is to use an online time tracking software such as the following:

Toggl : It's a free web-based time-tracking software that let's you track where you spend time while you are online. Please note that it's free for up to 5 users and comes with some basic features. I guess this should be enough for most individuals. You also have a desktop and a mobile version available.

Yast.com: Another simple, web-based time-tracking application is Yast.com - I've used it personally. It comes with a simple "1-click timer" --an audio-player like play and stop function to allow you to track time and add tags to help you remember for later. You may also use the iPhone and Android versions to track time while you are out and away from your laptop or computer.

Hope these help?