thanks for writing in.
Are you using Pro or X theme?
If pro, you can do it easily by using the element for header builder while in X theme, you will need to know how to add button in menu.
And for the contact number, you can make use of the topbar content located in your Launch > theme option > Header > MISCELLANEOUS
Then adjust everything with Custom CSS. You can make use of the Child theme CSS or Custom CSS located in your Theme Options > CSS.
For child theme setup guide:
Hope it helps.