Eclectus parrots are not only highly social, intelligent, fairly neat, and quiet, they are also fairly easy to train, as long as you use some measure of patience and repeat things over and over again. Training your Eclectus parrot, however, will prove to be an enjoyable experience for you and the bird.
Without proper training, the Eclectus parrot probably won't behave very well. You may experience things such as excessive chewing, pecking, nipping, and general naughtiness. They can even start to pluck their own feathers out, without the proper guidance. Think of your Eclectus parrot as a toddler.
Sometimes, the owner needs to be trained. For example, if your Eclectus parrot is excessively chewing items that you would rather he didn't chew you need to provide him with more appropriate chew toys. Then, when you find him chewing on items you don't want chewed redirect him to the acceptable items. Consistency is key here. If your Eclectus parrot is a biter, this is definitely a problem that needs to be addressed quickly. If your Eclectus parrot bites you, put him in his cage. Do this every time that he bites you, and eventually, he will get the message.
Aside from guiding him away from negative behavior, and reinforcing positive behaviors, you can teach your Eclectus parrot to talk. This is done by talking to him, and repeating what you say over and over. Start with easy words that have the ee sound in them, without too many syllables, and work your way up to longer words, phrases, and eventually songs.
You can teach your Eclectus to perform various tricks as well. For example, he may come to your shoulder when you whistle. He may even be trained to play dead if you really invest some time in him. Again, the key is repeating what you do, along with the command you give him, and giving him a little treat when he pleases you. It's really no different than training a dog. Eclectic parrots can even be potty trained - in a way. You can discourage them from eliminating all over the house by moving them to the place where they are expected to do this immediately. Eventually, they will start going to that specific place when they have to go.
Training may take a while. There is much to learn. Think of this as time invested in your pet, however, and remember that the more you work with your bird, the more he will trust you. From this trust, love will grow. Also, realize that as that trust and love grows, your Eclectus parrots greatest desire is to please you.