Use parts of sites in my site?

I have built my website myself. I used HTML, CSS, and JavaScript. I have a template that I really like the footer and the responsive Navigation menu. I was thinking I need to determine how I can repurpose my site like the areas of the template I like. I thought to myself don’t just assume… ask the experts at Sitepoint for ideas. Usually, that opens up ideas for doing things better. So I ask, is there a recommended way to do this?