GIthub two branch to Merge together, how to do?

Git鼓励大量使用分支：
查看分支：git branch
创建分支：git branch <name>
切换分支：git checkout <name>
创建+切换分支：git checkout -b <name>
合并某分支到当前分支：git merge <name>
删除分支：git branch -d <name>

Logically: OK

First, new a new branch dev on first in the master;

Then, on the dev branch code development; after the completion of the development, the new feature to merge the master branch, complete functional development!