What do I do when my Dutch Working Holiday Visa runs out?

Hey

I have been living in the Netherlands for the past 11 months on a working holiday visa. This is due to expire next month and I am getting stressed out because I do not know what happens next.

I would like to spend three months traveling around Europe before heading home. Do I need to go thru immigration somewhere on the day my visa expires? If I leave and take the train to Belgium or somewhere and do not go thru immigration - will it look like I have over stayed in the Netherlands? Do I need a stamp in my passport??? Can I just switch to being a tourist after being in the Netherlands?

I am from New Zealand and planning on traveling the world for many more years so do not want any problems with immigration anywhere around the world.

Thanks for any help anyone can give on this. I really need to get less stressed.