introducing new cat to a indoor/outdoor cat

I have an outdoor cat(male) that sleeps inside. He lives in our garage. he is 5 years old. We found him underneath our porch when he was a kitten, he was starving to death. Now about 3 months ago. another one showed up. Our existing cat was not happy. we have had our new kitty who is about a year old, in a big dog cage. The male has been hissing and such when we let the female out. These are both spayed and neutered. A few days ago the male got in a bad fight with the female. The girl, who is much smaller lost...What can I do to save these two cats?

Can the male see the female while she is in the cage? My cats are all indoor/outdoor. When a newcomer arrives, I put it in the screened cattery where the rest of them can see. They smell each other through the screen. they also see me feed and pet the newcomer. I also do the scent "tricks" so they all smell the same. I start letting the new one out when the hissing stops and the rest are more curious than intimidated by the newcomer. During these times I supervise the encounter. There may or may not be fighting but it usually depends on the newcomer whether he/she will submit to the alpha. There is no set time period on cat acceptance so be patient.