you can hit the post reply button, and below your text field you use the manage attachment button to upload the pictures.
instructions
likely your new camera uses high megapixel images... too big to upload. for those, you need to either setup a photobucket or imageshack or gmail's picassa account, and then use that site to upload the image, then use the yellow square icon above the text field to paste the picture's location.
pretty easy once you've done it.