If they are golden pheasants, you should have no trouble with them. Sometimes you'll get an agressive male and you may need to do something then. But 9 times out of 10 the goldens are the least agressive and the easiest to raise. They are very colorful and easy, so a good breed to start with.
For the pen size, if you can try to give them atleast a 5' x 10' pen for a pair. If you want a trio of them then probably better build a bigger pen closer to the 10'x10' range. Remember bigger is usually better when it comes to bird pens. Provide the hen with some cover, simply done by placing something in the corner so she can feel secluded and hidden.