Right click and save as the images and place them in your "/portraits" folder wherever you put your baldur's gate file. If you have not got a "/portraits" folder yet, then just create one by right clicking, choosing "new", "file" and then naming it "portraits".
These portraits exclude any I've used for my characters, so you might want to check those pages for portraits too.
Only portraits I've downloaded go up, and I only download portraits I like, and I try not to download portraits of actors or images taken from the covers of books I have read. You might also have trouble finding dwarves, halflings and gnomes - sorry. They are sectioned off in hair colour only because that's the first thing I know when I'm creating a character. One or two may sneak into the wrong section.
Baldur's Gate 2 (some).