Mitosis Question?

I know mitosis occurs in all somatic cells. Does it occur solely in the nucleus or is it the entire cell? I half understand mitosis. Can somebody please explain it to me? This is what I know: interphase cell grows, DNA replicates, and cell prepares to undergo mitosis. Then in prophase, the chromosomes uncoil and change from a blob of stuff into distinct chromosomes (with 2 sister chromatids? I'm kind of confused about this). Where does this exactly occur? Within the nuclear membrane? or the entire cell? All the spindle fibers and centrioles and all that stuff, where are they located within a cell? Cytoplasm? Can somebody please clarify? And then the cell plates forming and furrows in animal cells... where does that occur specifically? Thanks. :)