Assumption: Currently checked out branch is master and you have:

A - B - C - D - E - F - G - H master

Then `git branch newbranch` gives you:

                              master
A - B - C - D - E - F - G - H
                              newbranch

and `git reset --hard C` gives you:
        
A - B - C master
         \
          \
           D - E - F - G - H newbranch