Hard money lending.

I have been looking for diffrent types of investment to work with/on and would love any information I could get. I am curious how hard money lending works (on both ends). Also I have freinds that have holding companies that they hard money lend through. How do these work and why are they reluctant to give me much info. Is there a lot of capital neede to start thes types of investment? Could a hundred grand get me started? Is tis aventure not suited for a novice?
thank in advance
any info helps