I've setup my 890 for the TV, 2 dvds, a vcr, a receiver, and a cable box. So far, I'm really happy with it. The sw mentions being able to start your tv on a specific channel and I've read that the volume on the receiver can be set, etc, etc. But I can't find anything that tells me how to do those things. I see where I can send a "band" command to my receiver, but I have no idea what that does. It apparently doesn't let me choose am/fm or anything. Then there's a section that lets me choose IR commands such as 1 thru 9. But I have no idea what that does.

Is there somewhere I can look to find out more about programming the 890?

The help section of the Harmony software is pretty good, but only if you know what question to ask.
Failing that, googling a specific topic will probably give you some answers.

To start your "TV" activity on a specific channel, you can add extra commands. Run through the setup procedure for the activity, and answer one of the questions with "everything is working, but I want more control" (or something similar), and you get to a screen where you can add more commands to the start and finish of an activity.
Add the TV codes for the channel you want.
Many devices also allow you to switch them to a specific channel or input when they are first powered on. Again, the setup procedure for the activity will ask you the relevant question.

Not sure how you could set the volume of the receiver to a specific number, though, unless your receiver supports direct level setting from the original remote.

Basically, anything you can do by pressing buttons on the original remote can be done from the Harmony, either by pressing buttons, or by adding multiple buttons to a single button or an activity.

Watch TV type activities used to have an option to set the initial channel but I don't know if that option still exists. If so it's in the activity options section.

That option has been moved to the activity start/leave custom actions (start/exit macros). Review the activity and select the option "Yes, but I want to add more control of options and devices for this Activity", then click next/save a few times until you get to the custom actions configuration page.

If your receiver supports a set volume command or command sequence (read your receiver manual), then you can add it/them to the activity start custom actions, but you need to find the name of the command(s) first. To do that, try all the commands in device mode an pay attention to their behaviour. Else, teach it from the original remote.