How to make presentation's sections names appear in header?

In header I would like to put sections names (say Aim, Experiment, Results, Conclusion) of my talk. The idea is when I am on "Experiment" section's slides, all these names appear, say horizontally and only "Experiment" is visible while the other headings should blur or fade?.

So the question is:

1. How to break the presentation in sections or subsections?
2. How to make Keynote manage relevant section headings i.e. fading out irrelevant headings, colours, fonts

Of course I can write the names manually and for each slide do the necessay changes to the header. but lets face it: for 25+ slides this toturous.

I know probably I would have to reedit some master slides or this there any coding to be done?

I know this kind of things is rather simple in Beamer.

I would really welcome any bit of help. !!