You should include your target SEO keyword in three main places: the URL slug, H1, and title tag. These help Google understand what your page is about.
After that, you can include your keyword in a few H2 headings if it makes sense, but don't force it. Let your keywords appear naturally throughout your content.
The last thing you want to do is keyword stuff your pages or reduce the quality of your content just to squeeze in a few extra keywords.
As long as you're including your primary keyword in those three key places, creating relevant content, and matching the user's search intent, you're off to a good start.
Remember, there's no magic number of keywords you need to include to rank on Google. Focus on the topic and the quality of your content rather than how many times you mention a keyword.