This article hints at being able to unlock a bitlocked drive using:

Unlock-BitLocker -MountPoint -Password

However, I know diddly squat about Powershell and how to use the Powershell cmdlets to do what I want to do.

So, how do I do use the above to do something like the following?

Unlock-BitLocker -MountPoint D:\ -Password "password"

Currently about as much as I know how to do is start Powershell and that's it. I don't want to learn masses of Powershell to get to the point where I can do this. All that I need to know in enough to know how I can execute the commands that are pointed out in the first link.

So far in the powershell prompt if I past in:

Unlock-BitLocker -MountPoint D:\ -Password "password"

I get the following error:

The term 'Unlock-BitLocker' is not recognized as the name of a cmdlet, function, script file, or operable program. Chec
k the spelling of the name, or if a path was included, verify that the path is correct and try again.
At line:1 char:17
+ Unlock-BitLocker <<<<  -MountPoint D:\ -Password "password"
    + CategoryInfo          : ObjectNotFound: (Unlock-BitLocker:String) [], CommandNotFoundException
    + FullyQualifiedErrorId : CommandNotFoundException

This is most likely because I don't have any clue about how the commands on the initially linked page work in a powershell context.

This is so that I can answer my own question here:

Bitlocker and scheduled task (powershell) script to unlock non-system drive