guidance on a GUI

My app uses ci_simplicity to create this menu scheme. it is horizontal and not very appealing visually. I have seen more modern layouts, for example I viewed the Fusion Auth website. They have a vertical menuing layout that seems much more modern with submenu choices. 

Where can I find a tool that will allow me to create a more modern UI like the one fusion auth uses? Something with submenu items rather than all choices at a single level? What is such a tool called?

Attached Files

Thumbnail(s)
       

proof that an old dog can learn new tricks