There is also a button in the WYSIWYG editor.... its a picture icon.. or you can go the the media tab section and add them there.
Posting it to photobucket will save on bandwidth, but you lose "some" (very small) amount of SEO authority (you're linking out).
Also if you exceed your photobucket bandwidth for the month... it will pop up with that photobucket image... might not look too good width your clients.