Breadboarding an ATtiny861
This is a very basic introduction to the embedded playground, using an ATtiny as a cheap, lightweight example. This will focus on how to read a datasheet and properly wire the chip on a breadboard. For a crash course on breadboards, in general, head here. Connect 5V and ground to your bus rails; I'd recommend cutting the small end off of a USB cable and using the red and black wires for power and ground.
Near the top of the datasheet, you'll find the pinouts for the different packages.
First, the basic power pins. Find any pins containing GND or starting with V. For AVRs, there's usually "analog" versions of power and ground, usually starting with A. For now, we'll treat these as basic power pins.
Connect the two power pins to the power busses and ground to the ground busses.
Pins for Programming
For bonus points, connect a decoupling capacitor directly between the power and ground busses. The short version: decoupling capacitors protect the power source from noise or excessive power drain generated by the chip, decreasing noise and increasing frequency response to other chips using the same power source. The size of the capacitor isn't very picky until dealing with high frequency applications with high precision requirements. One recommendation says 100 nF per VCC pin connected; this accounts for multiple pins on multiple chips. Atmel has a whole application note on their recommendations (TL;DR, "...a 0.22 μF capacitor is recommended. In many cases, this will be overkill.").