To get started, I purchased an RTL-SDR dongle and antenna kit from Amazon. This came with the dongle, an antenna, and some equipment for connecting the two. The kit came in a couple of business days. More information about the dongle can be found on the About RTL-SDR page. Some things to remember from that page include:
RTL-SDRs are receive only. You cannot transmit using these. To upgrade to one that also transmits will append a zero to the end of the price. I am planning on buying such an SDR when I am more experienced with the receive-only SDRs.
RTL-SDRs are not standardized pieces of hardware. There are many configurations based on the RTL2832U chipset, a chipset originally intended designed for TV tuners. Therefore, you should be aware of the specs of the particular product you are buying. For example, the product I purchased from the link above uses the Rafael Micro R820T/2 tuner, which has a frequency range of 24–1766 MHz.
No one entity controls RTL-SDRs. These are like Arduinos in the sense that there are many manufacturers that produce products that are basically the same, but there are some important differences when you get up close and personal.
I then followed the installation instructions on the RTL-SDR "Quick Start Guide." I did this on my laptop running Windows 10. This involved downloading a .zip folder and running a batch script. The directions are pretty clear, so I won't comment on the installation process. I didn't run into any issues.
I opened SDR# after installing the appropriate drivers. The SDRSharp Users Guide is a good way to get familiar with this software. This is a very intuitive program. The frequency is prominently displayed at the top of the screen. You can click on the spectrogram or waterfall to change frequencies, although the default frequency steps are rather coarse. You can adjust this by opening the radio tab on the left-hand pane and selecting the frequency drop down menu to a finer step size. You can manually type in the frequency, or increment or decrement individual digits by clicking on the frequency at the top.
A couple of observations:
After just a few minutes, the RTL-SDR dongle got quite warm. I unplugged it to let it cool to prevent any damage.
There is no lower bound to the receive frequencies, even though my RTL-SDR came with a lower receive spec of 24 MHz. I need to do some testing to see if it can, in fact, receive signals that low.