You need to allow Adobe Flash in Google Chrome in order to use our image upload tool. Simple click the "i" icon and select "Flash > always allow on this site" and then reload the page.
If you still have problems then there is a more extensive guide here: https://support.google.com/chrome/answer/6258784
For other browsers, see Adobe's guide here.
Alternatively, visit this page and follow the instructions on how you can easily prepare and send us your images manually.