ok in adobe photoshop, i know the screen option makes everything black transparent... but how about white? what if i want something white transparent? how would i do that?

What do you mean by white transparent? I don't think that exists, but you can make the background white...?

in adobe photoshop, theres a layer blend option called screen. if you select it, it will make everything black transparent on that layer. this is very useful for lens flares. but what if i wanted the darkness to appear, and the white to disappear?

maybe try the lighten option?