Hair expert? I need some advice.

So I need some advice about lightening my roots. I have an appointment in about a week and I need to have an idea of what I'm doing by then so:

I have naturally dark hair and it's pretty much currently coloured the same as in the first pic.

I want to achieve a colour more like the second pic.

Is it possible to lighten the hair in between the foils so that there is less of a contrast between blonde and dark?

Can you explain how it's achieved so that I can talk to my hairdresser about it please.

Thanks