OptimizePress requires certain permissions to be set on your server in order to upload images to your site. Follow the steps in this guide to fix this issue:
1) Ensure that the wp-content/uploads folder on your server has the permissions set at 777. This means that our system can write images and files to this folder. You can set the permissions in most FTP software by right clicking on the folder and setting the permissions.
You can also change the folder permissions inside Cpanel file manager system
2) Check that you have sufficient webspace and bandwidth on your server and have allocated a sufficient amount to this website/domain if you are on a reseller account.