This topic was covered in Teen Time, but here is a deeper presentation on ‘satan’.
The Biblical version of satan is the tempter, the one who challenges us to turn away from God’s desire for our lives and follow another path. The Tempter was part of the heavenly community, not an occupant of another level of creation.
We have to separate the Biblical understanding of satan from the popular cultural version of a cosmic personification of evil locked in perpetual battle with God. In that fantasy satan has equal power to God (an unequal battle would be over very quickly). That fairytale might make for good TV drama, but it is a horrible and inaccurate theological concept.