If you are on iOS, just enter the details of your document, then tap the share icon at the top right of the screen and choose "Print".
If you are not on iOS, you can click on your document, then press the three points at the top right and choose "Print".
The application then suggests printers you can choose. If your printer does not appear, you must configure it for your device by following the steps on this link: http://bit.ly/2kSR3w6
However, some devices do not have the updated version to use this printing feature. To find out which version you have, check out this link: http://bit.ly/2yvSZjh
Devices with versions lower than 5.1 will not be able to directly print their document(s) via their smartphone or tablet. You can, in this case, choose the "Share with" option and send the document to your email address in order to print it via the internet.