MPP Tracker

Refering to Maximum power point tracking - Wikipedia

The MPPT regulates the voltage to the value required (U*I=maximum).

But how to regulate a Solar Module?
For Example my own small 6V, 400mA Module?
How can i regulate it like the MPP Tracker do? And set it so 5.7V e.g.?

What kind of load are you going to put on it? As far as ican see I don't see a problemin creating one of those with an arduino, all seems easily possible, perhaps some more complex programming than most projects but doable

MPP trackers are essentially switch mode voltage converters, with intelligent software that juggles the load on the Solar panel
to obtain the maximum output power.
There are many common algorithms used for the load juggling, but basic idea is to measure the output power from the Solar panel
and then change the load in some defined manner, and then see what happens to the output power.
Its not that hard to do, but you do need a good understanding of how to design switch mode power supplies to keep their efficiency
high.
For very small Solar panels is not worth doing,as the output power increase is at best around 30%, and unless you can source all the parts
for the tracker for next to nothing,its usually cheaper to just buy a 2nd solar panel.