git checkout -b name-of-your-branch
git branch -d name-of-your-branch
Bootstrap makes it easier to layout web pages by using a grid system made up of rows and columns. Rows are horizontal and columns are vertical. You can have as many row as you'd like, however you can only have 12 columns and they are always nested inside rows. Click here for examples of the grid system.
When you push up your changes to Github.com while you're on a branch, you create a separate branch on Github.com. In order to get your changes from your feature branch into the master branch, you need to merge those two branches together. To do this, create a pull request.