How does a woman purify herself from major ritual impurity (janabah) while she is menstruating? And does this lift the state of major ritual impurity, leaving only menstruation, or not?

It is permissible for a menstruating woman, if she becomes ritually impure (junub) or was already ritually impure when her menstruation began, to perform a ritual bath (ghusl (definition)) for major ritual impurity (janabah (definition)). This is so she can benefit from the permissibility of reciting the Qur'an without touching the Mushaf (definition). This ghusl is like any other ritual bath: she begins by washing the parts of the body washed during ablution (wudu'), then pours water over the rest of her body. By doing so, the state of major ritual impurity (janabah) is lifted, while the state of menstruation (hayd) remains.