Summarize the following:
You will need more than one tank in order to breed tetras, so get another one if you do not have one already. You can use a 12 x 8 x 8 inch (30 x 20 x 20cm) tank to breed your tetras. You will use this tank to bring a male and female tetra together for breeding and also as a place incubate the eggs and baby tetras. You can set this tank up similar to how you have your normal tank set up. Just keep in mind that the water will need to be soft and kept at a specific temperature and acidity in order for breeding to happen. When you are breeding neon tetras, the water in your breeding tank needs to be kept at about 77 degrees Fahrenheit. The water also needs to be soft (low-mineral content) and slightly acidic (with a pH of 5-6) in order for neon tetras to thrive. This type of environment is what best mimics the natural environment of a neon tetra. If the water in your tank does not meet these requirements, you will need to:  get a tank thermometer to monitor the water temperature. test the pH of the water daily using pH test strips (available at pet stores) mix one part tap water with three parts reverse osmosis water to make soft water for your tank OR use fresh rainwater A filtration system can help to remove waste products and bacteria from the aquarium, which will protect the health of your tetras. A filtration system can also remove bacteria from the aquarium and keep it looking its best. Corner box filters are ideal for breeding tanks because they are gentle. Tetras need a dark environment to thrive, so do not place your tetras near a sunny window or in another place that gets a lot of light. Tetras do not need total darkness, but they do need to be placed somewhere that gets only a small amount of light each day. You may even want to cover the back and sides of your tank in dark paper to block out excess light.

Summary:
Set up a breeding tank. Prepare the water. Get a corner box filter for your tank. Place the tank in a dark or low-light place.