Design my ionic2 application

I created an ionic2 application with all the functionalities that i needed,now i want to add some design to this application beacause it looks ugly.I want to add some sidemenus and other new components.
Any idea of how can i do this?

To add new components, you just have to code them like you wrote the initial app. As for the sidemenu, there will be some refactoring due to the structural nature of that component.

For you style question, it is just CSS, so dive into either changing the SASS variables, or overriding/extending the existing CSS.