It sounds like the idea is to provide a safe path if lightning were to strike the antenna.
You might already have a grounding rod in the ground for your home electric service. Usually it's either at the electric meter or at the transformer (in which case it's probably not accessible). If you are planning on installing the antenna near that, you could wire it to that.
If you don't have a grounding rod you could wire it to one without connecting the rod to your breaker box. The risk if you don't connect it is that whatever equipment the antenna is connected to could be damaged if there were to be a lightning strike. But at least it won't explode or catch on fire like it would if the antenna as ungrounded. If you do tie the grounding rod to your home system, you risk introducing problems if it's not meant to be wired that way. Even with proper grounding, a lightning strike to the antenna will probably damage whatever it's connected to, no matter what. If you are in an area that gets a lot of lightning you could look into additional lightning protection in addition to grounding it.
I would lean towards putting it in the attic if you can, It will be safe from lightning and other weather like wind that could blow it out of alignment or moisture that could cause corrosion over time. As long as you do a continuous run of good quality cable there should not be that much loss.
To get the best signal, you need a clear line of sight to the tower as much as possible. Higher off the ground is better (in the attic is better than near the ground), and correct aim is critical. A more directional antenna has more gain. In general amplified antennas are not worth it.
