here's a brief recipe: Cube chicken breast. Toss in a wok (Deep frying pan will work, but a wok is ideal). cook until about half done. Then add orange juice, brown sugar, orange zest (grated orange peel, basically). this should basically make a really sweet orange juice. Now, to thicken it into a gravy use corn starch slurry (corn starch and cold water). keep on low heat until thickened and the chicken is done. It's far from genuine orange chicken, but I call it "cheater orange chicken".
the same basic orange sauce also works for pork and steak, but the mild flavor of chicken allows the oranges to shine best. also, if your sauce doesn't thicken correctly, try adding a couple pinches of baking soda first. acidic fluids don't thicken too well, usually. so turning the sauce a little more basic (pH wise) can help it thicken.
also, once you've nailed the sauce, you can try adding a twist here or there. pumpkin pie spice especially works well. or just plain cinnamon. it'll add a touch of sweet.