Best way to introduce mare to very dominant gelding?

At my barn to introduce a new horse they keep the new horse either in his stall and let out to a separate pasture for a week. This way there isn't as much fighting and they can settle out the pecking order. Talk to your barn owner to do this. Also when your mare first arrives walk her around the fence of the pasture allowing her to see the new property and horses. Allow interaction but keep it small and short when they talk over the fence. Because she isn't dominant she will be less likely to get into big fights over the dominance issue. There is also less likely of attacking because of the fact she is a mare. Just slowly increase the time spent with and around the herd and there is a smaller chance of her getting attacked :)