Make sure that you have the correct year selected before clicking delete. This will delete the year and all of the galleries and images it contains permanently.
Make sure that you have the correct gallery from the correct year that you want to delete before clicking yes (select one from the list before clicking delete gallery). The gallery will be deleted permanently.
Allowed file types are .jpg, .png, .gif, and .zip. If you want to upload many images at a time, put them in a zip file and upload it. Make sure you are uploading to the right gallery (select one from the list before clicking upload images). The server might take some time to upload all files.
Are you sure that you wish to delete all of selected images?