The branches overview shows the branches that are already existing. By clicking on a branch, the details page of the branch is shown.
The tag "Default" shows which branch is currently set as the default branch of the repository in SCM-Manager. The default branch is always shown first when opening the repository in SCM-Manager.
The button "Create Branch" opens the form to create a new branch.
New branches can be created with the "Create Branch" form. There, you have to choose the branch that the new branch will be branched from and to provide a name for the new branch. It is not possible to create branches in an empty Git repository.
This page shows some commands to work with the branch on the command line.