Minimum tank size for a pair is a 20 high, angels grow tall and a 10 gallon doesn't provide that height. Fins have noting to do with the sex of an angel, the only reliable way to tell is when they are actively spawning.
They might spawn on that decoration, angels tend to like taller objects at a bit of an angle. I've been using pieces of pvc pipe for years, others use slate, some use plants, all pretty much personal preference.
Please understand that raising an angel spawn takes tank space, as well as daily hatching of live baby brine shrimp for any success. A small spawn is 200 fish, each fish raised to dime body size will need 1/2 gallon of tank space, nickel body size will need a gallon each. There is also maintenance required beyond caring for the average stocked community tank, as well as some specialized, but easily made at home equipment.
I sure don't want you to be put off with this, but you should know these things going into it. If you would still like to breed angels I, and several other members would be more than happy to help you with this. There are plenty of tips, tricks, and cheap ways around things that we have picked up, no reason for you to reinvent the wheel!