git - new user trying to do pull and getting some confusing messages

I think you missed the name of the remote when pulling:

git pull <remote> my_branch_name

Run this command:

git remote -v

And check what is the name of the remote you want to pull from

EDIT:

If you are new to Git, I would recommend you this book. It covers from basic to advanced topics, is easy to understand and to read

As the first error message indicated, you need to tell git where to look when it pulls for that branch:

In Git 1.8 and up, ensure you've checked out develop and run:

git branch --set-upstream-to origin/develop

or the shorter:-

git branch -u origin/develop

In Git prior to version 1.8:

git branch --set-upstream develop origin/develop

Once you've done that you can git pull without having to specify the remote or the branch.

If the remote origin is not yet set up, first run:

git remote add origin url

try this command:

git pull origin master
git push -u origin master

You could specify what branch you want to pull:

git pull origin master

Or you could set it up so that your local master branch tracks github master branch as an upstream:

git branch --set-upstream-to=origin/master master
git pull

This branch tracking is set up for you automatically when you clone a repository (for the default branch only), but if you add a remote to an existing repository you have to set up the tracking yourself. Thankfully, the advice given by git makes that pretty easy to remember how to do.

--set-upstream is deprecated in git 1.9.x, apparently. Going forward you'd want to use something like

git branch -u origin/master

assuming you've checked out master already. If not, git branch -u origin/master master will work