Star shapes are created in Photoshop either via the polygon tool or you can create them via brushes or pen tool etc to create a more organic design. You can customize the toolbar so you may find it in a different location depending on your customization.
They can be added via the polygon tool. They need to be applied by changing the ratio, set that to less than 100% and then you will see the required design and set it to 5% for an intense artwork. You can also change the number of points along the top of the bar. You can also round the artwork as well using the field next to the number of points
You can set up a quick access tool preset in the top left so you can create a 5 point design or a curved design preset and more. I love the tool presets though I wonder if they are used that much, tucked away in the top left. You can set them up for all of the tools but they are really useful when it comes to vector artwork. Simply go to the tool presets and select one and it works in both shapes and pixel mode, it creates the artwork using the preset as you drag. It works using points as well as ratio and color (if selected) as well as tool options such as fixed size. You can also create your own via the right side menu and create command. You can display all the available tools, personally I just keep it relevant to the tool that I am currently using. In pixel mode, shape layer presets are applied as a pixel and use the current color and don't use the stored color. The tool preset does not store transforms or effects etc. You can rename and delete the tool presets
They can be added as a pixel design, perhaps add it to a layer, or it can be added as a vector layer and the vector layer offers more flexibility as you can re-size the design, you can rotate it, add other transforms, combine it with other shapes and much more. It can also be added as a path. As a shape, you can add effects via the filter menu as well as layer styles such as drop shadows to the shape. You can add them as a pixel but they are then added to a layer or the background and cannot be easily be modified other than adding effects etc
As a pixel, you can then warp and distort as well as add filter effects etc such as blurs
You can change the number of points via the top bar but that is only used when you create a new artwork, if you want to interactively modify the number of points, radius etc then you will need to use the properties panel found in the window menu.
They can added as a vector layer can be combined via the layer menu and using the combine commands such as unite etc and literally millions of different designs can be added.
You can create a design hollowed out design using subtract front shape command. Create your first shape as a vector layer. Hold down the alt / option key and drag the design and duplicate it. Re-size the vector and make it smaller via the bounding box. Use the alignment tools to align center and middle. Go to the layer menu and combine shapes and subtract front shape.
If you add the design as a vector, you can also tweak the individual points, inner and outer, by using the direct selection tool found in the tools panel. Select the points and drag them in different directions etc