I sell new locks with 2 keys for $10.50 or I can charge $15 to make a key for your lock and $1.50 for a second key. They aren't economical to rekey or make keys to.
If you are dead set on it, take a thin hacksaw, cut a fraction of the cap off at the back, pry it up and remove it. The last pin is a solid pin that is a retainer. Once that pin is removed you can either remove the other pins and springs or shim the cylinder and use a follower. Making a key is rather simple then. To reuse the cap, flatten it then bend it in a V shape lengthwise in a vise. Once you have your pins back in and the retainer pin place the cap with the peak of the V facing up, as you flatten this out it will spread and lock into place.
As you can see, it is a lot of work unless your time isn't worth much or you just like a challenge.