Log in to Photobucket click on to the LIBRARY tab at the top
On the left is a list of albums - Select the album you want to load photos to (or create and name a new one)
On the right is a view of the album. There will be a white square for you to load images into:
To drag and drop you will need to have your PC set up so you can see both the photobucket page and the pictures you want to upload, e.g
Click on the pictures you want to upload to select multiple pictures, hold down the CTRL key and click on each one in turn. Drag the selected pictures and drop them on to the white square shown above. If the album already has pictures in it, the square will usually be in the top left corner and the same size as the image thumbnails.
Alternatively, if you click on the white square in Photobucket you get a file browser window and can then browse to and click on the photos you want to upload selecting multiple files by holding down the CTRL key and clicking as per above once you have selected the files , click on the OPEN button on the file browser window
In both cases you will see the swirly circle of boredom in the white upload box, and a blue progress bar at the bottom of the screen.
When the progress bar is full you should see your images appear in the Photobucket browser window.