One fantastic tool for the electronic hobbyist is LTspice and it is free! If you're reading this, you're already using a computer. So why not also simulate an electronic circuit before you build it? Here are just some of the reasons why you might want to use LTspice:
Linear Technology maintains and distributes LTspice. It is provided to allow customers to test and try out their products before committing to buy. They make the software freely available. Just keep in mind that only paying customers get “service” for any software bugs or enhancement requests.
There seems to be an LTspice wiki that has some advanced material and pointers to tutorials.
No. When you learn it step by step, it very easy. Most of the challenge is simply becoming familiar with where things are and how to accomplish certain tasks. Once you've walked through these things once, you'll become immediately familiar with it. Stepping through it's use, you'll put some simple circuits into LTspice immediately and run simulations. Instant gratification!
So I won't drag you through a bunch of documentation to read first. We'll start right away doing things!
After you start using LTspice, you'll wonder how you ever got by without it!