KidsHealth and AVERT are two websites that provide online pictures and resources to help a girl through puberty. Menstrupedia is a more basic website that is helpful.
KidsHealth provides a list of articles covering various topics involving puberty, including breast development and bras, menstruation, sanitary pads and tampons, and cramps. Skin problems are also discussed.
AVERT offers a basic discussion of puberty accompanied by drawings of breast development, body hair development, locations of sex organs and pregnancy. Each set of drawings illustrates the body changes a girl can expect from age 7 through age 19.
Menstrupedia provides a short, basic introduction to puberty for girls. Drawings depict breast development, pubic hair development and overall growth from age 7 or 8 through age 19.