how to copy code from old branch to new branch and make new branch in github code example

Example 1: create a new branch based on another branch

//when on branch 'dev' make branch 'myFeature' off of 'dev'
git checkout -b myfeature dev

Example 2: createa. branch off of development git

//when on branch 'dev' make branch 'myFeature' off of 'dev'
git checkout -b myFeature dev