I also use photobucket.
same as above, just place your cursor over the pic, and a popdown menu will appear. select and copy the image code. then just paste it into your message, and once submitted, the pic will show in your post
also, in photobucket, you can set it to automatically format the pix to the size you want them to be. for instance, i usually post pix of 700x size, so i've got it set to have them sized that way when they upload from my computer.