noobe Git user question on branching

ok after days of trying to git proper and being a complete noob with this having done neither git or svn before and even restarting from scratch quite a few time’s already including reinstalling and deleting my fork
because the remote stopped updating
this is what ive done so far that i understand but i have a question’s

first were is the best place to post questions on this forum or elsewere?

i got git and tortoise git
i set it up using the help guide
i then when to the monogame wiki and started following the instructions

i made a fork to monogame
i cloned it thru tortoise to my drive
---- here is my first question
the Third party stuff doesn’t clone over what is the proper way to handle that?
continuing without doing anything with the third party stuff

i then remoted that cloned folder to monogame using bash
---- the next step is a bit confusing
git checkout -b scratch
do i use git bash on my local cloned drive to do this ?
and am i supposed to do this on github first ?
then clone that to my local drive as well in a different folder?
just thru bash from a different folder then were i cloned my fork ?
or thru bash from the same cloned folder ?
or use tortoise git if so were do i do that from in tortoise ?
and what about the third party stuff again