You only use PictureProject to get the pictures from your camera to the computer. To get them on photobucket you have to actually be at that website and be registered.
What I did with mine is I changed the file that PictureProject transfers the file to on my PC. Its kind of a pain the way the pictureproject default is set up. It saves it to a folder deep in PictureProject whichis under Program Files/Nikon/PictureProject and each time you transfer from the camera it creates a new folder within the picture project folder. This makes it even harder to find the first time you go though it. I hate that.
You can change all that. First create a new folder in an easier to find part of the computer (usually under My Documents then My Pictures, {File, New, Folder, then name it whatever you want, ie; 2006 Pictures) I save all my pictures in order I took them each year. Then once you create the folder go into PictureProject. Go into Transfer. Options. Click on Browse next to the box that says Transfer destination folder: Then find the folder you want your pictures saved to and double click that folder then click OK. You can also unclick the "Create a new subfolder for each transfer", unless of course you want a new folder.
Thats the way I do it. I then find it much easier to find the picture folder when I want to upload pics to Photobucket.
Once in Photobucket, click on browse, then click on Look in: and find the folder. Double click the photo, then submit.