There are many ways to go about this. Here are the two main ways:
1. Get a female. Quarantine for several months and get at least a couple of fecal checks done. House them separately most of the time and put them together periodically for breeding.
2. Get several females, quarantine and fecal check them, then put them all together with your male in a very large outside enclosure with lots of hiding areas and sight barriers. Then watch very closely to make sure they all get along and the male isn't too aggressive with any of the girls. Separate if necessary.
I would NOT recommend getting a single female and plopping her into your existing enclosure with the male. That will almost certainly end badly.
Some people are able to do this indoor but keep in mind, the bigger the enclosure the better. and yes you need multiple females... if you only get one, the male will just follow the female all day long... this will over stress the female and can be fatal...
Tortoise-keepers who have experience and know what to look for do have success breeding indoors. But for the inexperienced tortoise-keeper you will have better luck with them being in a large outdoor habitat where nature can take its course.
Tortoises are solitary by nature and chase off other tortoises that come into their territories. It is only natural for your existing tortoise to not want another tortoise in his habitat. If he were going to want to breed, he would go looking for a female, not the other way around.
The Testudo species are some of the more obnoxious tortoises. They are pretty darned aggressive towards other tortoises. A male/female ratio in one indoor habitat would certainly have your female stressed out and hiding all the time.
Ok so maybe I should wait til I know better and more and have more space outdoor wise to do so. I love in Washington so the weather outside right now it not good. Is breeding a spring time thing? Or summer time?.... Because here I'm sure it's way to cold for him to be outside...