Thanks for starting to contribute, this is very welcomed!
First off you don't need libdiscid or discid installed at all, both are completely optional and you can easily run Picard without it. You only need to have this if you actually want to have the disc ID feature available (which you definitely don't need for this issue here).
If you really want to install it, you have to place discid.dll in your %PATH% variable somewhere. First get discid.dll from https://github.com/metabrainz/libdiscid/releases/tag/v0.6.2 . Make sure you use the correct version (32 or 64 bit), this depends on your Python install. So if you have 32 bit Python installed you need the 32 bit discid.dll, even if your Windows is 64 bit.
One easy way to make sure discid.dll is in your path is to copy it somewhere globally, e.g. to C:\Windows\system32 . I actually prefer to have it in the folder where I checked out Picard. Then to install discid with pip I open a command prompt in the folder I checked out Picard to (it's Z:\win32\musicbrainz\picard\git in my case) and run:
set PATH=%PATH%;%cd%
pip install --user discid
The set PATH part makes sure the current directory (which is %cd% referring to) is part of the %PATH% variable. Then the pip install will succeed. The change to %PATH% is only temporary, but that's fine. When running Picard it will also find discid.dll at that location automatically.
As a last note I would suggest you ask further usage and development setup questions, that are unrelated to the actual task here, at https://community.metabrainz.org/ . It's easier to discuss such things there 
It worked. Thanks a lot.
And yes, I'll make sure I go to the community for such queries in the future.