Click the round plus sign in the lower right corner of the screen. This will bring up the file chooser dialog of your device. This will look different depending on your device and the apps you have installed but will look similar to below.
Find and select your chart. If you are running Pattern Keeper on an emulator then you can not access files on your computer directly. Check the instructions for your emulator on how to access files. Instructions for Bluestacks
The app will process for a short while and then ask you about the overlap used in the chart. Many multi page charts repeat a couple of rows/column on page breaks. It is important that the app knows how many rows/columns are repeated so you don't end up with duplicated stitches in your pattern.
If the app recognizes the designer of the chart it will simply ask you if you want to import with the overlap used by that designer and you can just click yes.
If it is an unknown designer you will first be asked if the chart uses an overlap as a yes/no question. If the chart uses an overlap you will get a dialog where you can configure the size and placement of the overlap.
Pattern Keeper will then process your pattern. When the import is finished your chart will display on of three status symbols telling you how it went.
Import was successful. Click on the chart to check on the imported result.
Not completely successful
Import was mostly successful but some information was not read automatically. In some cases you can input the information by hand. Click on the chart to find out more details about the import.
This means that Pattern Keeper failed to import your chart.