How can you set up LED lights on a poster for a projecT?

First of all, you'll need to know some basic circuitry principles and you will need:

A battery (9V is a good choice for a large selection of LEDs)

A collection of wires

Some splicing caps (or alligator clamps attached to your wires)

A resistor of the correct resistance

Some LEDs.

The resistance for the resistor is a bit of a ball park thing - anything less than a full order of magnitude (10x or 0.1x) shouldn't cause a significant difference.

Ideal resistance can be calculated using a number of parameters:

Battery Voltage

Voltage drop across LEDs (red and green are 2, blue and white are 3.5 (and blindingly bright - they're meant for illumination, not decoration)

desired current (about 20mA for most cases).

Number of LEDs to connect