Preload in Hook?

I'm very new to this aspect of websites., please forgive me if I've completely confused things.
And thanks so much for any help you can provide.

I was testing my website speed with Google Pagespeed.
I got this recommendation: Consider using <link rel=preload> to prioritize fetching resources that are currently requested later in page load.

I may be far off base here.., but I tried to use an Element hook in the wp-head.

I'm not sure if this is correct AT ALL.
I was hoping if it was/wasn't if you wouldn't mind pointing me in the correct direction?

Much Appreciated,
Don