Header Navigation

Site URL: https://tetra-wisteria-snzf.squarespace.com/config/

Hi all!

I was hoping for some help with modifying my header. As my home page is actually a portfolio main page rather than an individual page (meaning my main landing pages are not actually pages, rather they are projects), this means I am not able to put my projects into my header as pages to navigate to. Is there any way to hard-code navigation links into my header? And ideally control the position of them? I've attached a photo of what I'd like my header to look like (Boehm Construction), and what mine currently looks like.

Lastly, my services section has two available option. I was hoping that I could implement both options into my header with the hover feature (most common feature for options in a header).

Ex. Services -> New Construction

or                     -> Renovations

Thank you for your help and guidance!