Step one move mouse curser over to the down arrow thats to the right side of where it says galleries (circled in blue)
Step two click where it says upload to gallery
Step Three this brings up a list of contest going on an other galleries look for the contest on the left side
Step four in the middle beside the name of the gallery it has manage images (circled in blue) click that
Step Five click here it says add file on the top left (circled in blue)
Step six click Start Upload an it will add the image automatically
Step seven look for uploaded image and click Edit if you want to add a description an dont forget to push the save button