The only way you can do it is by collecting spore and germinating it. Although this process is very different from flowering plants, it is not that difficult if you follow some basic steps. Here's a link to one of the world's leading fern hobbiests, Keith Rogers. This guy's got one of the most diverse fern collections in the world, and he's really nice to boot! PF

Here is a link that might be useful: Keith Roger's Method