Thanks for clarifying your question. The attached link gives step by step instructions for building a homemade generator for a windmill.http://www.mikeswindmillshop.com/howtow ... rator.html
As indicated you need to use a copper magnet wire. Note the wire appears to be bare copper wire but actually it has a nonconductive coating. The article tells you how to wind the stator to achieve various output voltages.
When the generator is connected to a load (for example a light bulb or heating element) the current will flow in accordance with Ohm's law
Voltage = Resistance x Amperage.
In this case the resistance is the internal resistance of the generator plus the resistance of the load. So to answer your question (how to get more amperage with less speed) you can increase the amperage through the load by increasing the output voltage of the generator. You increase the output voltage of the generator by increasing the number of windings. http://www.whitbyhydro.on.ca/pdf/5.2.C_GenBasics.pdf