Note: Make sure you always read the online version of the documentation here. Some new things may be added/changed over the time.
ImagePicker is a quick and easy way to upload images for profile avatar, profile header/cover (like YouTube/Google+), generate thumbnails or just when you need a simple but yet powerful image uploader.
You can take pictures with your webcam or phone camera and then you have the option to crop/recrop, rotate or delete.
To get started with this script start with the Installation and How to use it sections.
Then you can take a look at the Options and Configuration sections
And finaly you can see some Examples.