1- Select the pictures you want to upload to the frame (do a quick test first with 2 or 3 pictures max.).
2- In iPhoto / Photo go to FILE menu then inside click on:
3- In the pop up menu make sure to choose "original" in the first line.
don't resize the picture so that they don't get too small on the frame screen.
4- Once done click ok and in the next window select the folder where to store them.
5- now you are ready to upload to you pix-star.com account. Log into it, then inside go to the left / middle
View my web albums
inside you create a pix-star web album then you can upload them there.
Another option here is to send them by email to the frame as u probably usually do. This is ok if you don't have too many pictures otherwise it's better to arrange them into web albums as said above.
Enjoy your Pix-Star!