Firstly, if you did not recieve and email invite, you cannot (and I repeat) cannot upload/post/share your photographs
Uploading photographs is via invitation, you might argue why do it this way when the web is moving in the direction of anybody and everybody can do upload anything (flickr, facebook, photobucket, zoopy, yadi-yadi-yada)
That's exactly why, a different approach was/is needed to keep the focus on 'photography'.
Secondly, if you have recieved an invitation and accepted it --- you then need to login, and at the top right of this screen you should see your avatar/profile icon/picture --- click on it
You should then see an 'upload' button on the right -- click on that, and bada-bing-bada-bang you are ready to upload.
Oh, only one photograph per day per 'grapher on any day.