Complex sentence: She was an editor (1881-1917) of the Woman's Journal, of the major publication of the women's rights movement at that time, first as assistant to her parents and after their deaths as editor in chief.
Split into simpler sentences: She was an editor (1881-1917) of the Woman's Journal, the major publication of the women's rights movement at that time. First as assistant to her parents and after their death as editor in chief.