Well, there are two things that you would do as the basis of flight recall. Establishing a bond with your birds, and target training them.
You can establish this bond by convincing your birds that being with you is the fun place to be. Spend time talking with them and bribing them with their favorite treats. (Nut fragments or seeds that they don't get with their regular meals.) The more they want to be with you, the easier it will be to train them to come to you on command.
And then there is the target training, which will provide the framework for following your directions. You can start target training in the cage using a target stick. (Chop sticks make great, inexpensive target sticks.) The way this works is to get your bird to associate said stick with his favorite treats. For more curious (or aggressive) birds, this will prove rather easy. Just slowly put the tip of the stick between the bars of the cage, being careful, of course, not to frighten him by kind of chasing him with it. The point is for him to come to the point of the stick and touch it with his beak. (Or for a less adventurous bird, you can start by rewarding his taking even a few steps in the right direction.) Using a clicker to indicate approval, followed by the reward of a treat, works quite well for this. But simply giving an enthusiastic "good job!" works too. It's really about what works best for you.
Here is an example of target training by our own Katie_fleming, who has posted several videos of her training sessions with her eclectus parrot, Jasper: [ame="https://youtu.be/TXzwJr8zRww"]Jasper's Tunnel Walk (Eclectus Parrot) - YouTube[/ame]
In this video, she uses the clicker method to reinforce the moment when he has accomplished what she has asked of him. The clicker becomes the "bridge" to the treat.
Once your bird makes the association between touching that stick and getting a reward, you'll be able to point anywhere in the cage and he will go. (Make sure to do training in between his meal times, when he'll be hungry enough to be food-motivated.) Eventually, when his in-cage targeting becomes reliable, you can begin to target him outside of the cage. The natural progression will eventually take him to flying over to your arm on command.
Now, if your bird tends more toward the shy or timid side, you might have to work on the trust between you more before beginning target training. Your bird has to feel safe with you. This can be accomplished by simply sitting by your bird's cage and reading to him. Don't push the interaction too quickly. Try to build the bond, first. And try not to make your movements too swift or jerky. Keep them smooth and relaxed. And keep your tone soothing.
I hope this helps. If you have further questions, please don't hesitate to ask.