How do i make a gradient for stuff on my layout

you can use that website to generate the gradient you want
for example if you want to change the top, you can do that:
nav .top { background: linear-gradient(90deg, rgba(2,0,36,1) 0%, rgba(35,35,164,1) 35%, rgba(0,212,255,1) 100%); }
ofc its an example with the default blue gradient from that website

I meant the top bar and other stuff, not the background

Here is a cool website to make css gradients :)