Start with HTML and CSS if you cannot yet read a page
The short introductory course is the lowest-friction entry when tags, document structure and CSS properties are still new.
Choose the diploma when you need more repetition
The longer HTML/CSS course is more appropriate when you want to spend substantially more time building page structure and styling rather than only learning the vocabulary.
Add hosting and server concepts after the page itself makes sense
Deployment concepts are easier to understand once you can already build a basic site. Otherwise hosting terminology becomes another abstraction stacked on top of HTML/CSS confusion.
What these courses do not cover completely
Modern web development also includes JavaScript, accessibility, version control, application frameworks, security, testing and deployment workflows. Treat this path as a foundation, not the entire profession.