You need low humidity and something to absorb moisture like a paper towel. I always use old telephone books.

Some flowers have too much moisture to press and will get moldy. Those can be put into a dessicant to dry in their natural shape.

instead of the dessicant is there a way to press them? I've seen other floral preservation artists post their flowers and they come out so white. Is it possible theyre coloring them after?

You can break the flower apart, slice up the base of the flower, press them separately, then glue them back together. You can also slice them down the middle and press flat. If you do a search you can find info on how to press thick flowers. Colors fade after time.