I need the right tools > I get lost!

Responsive Web Design Projects - Build a Technical Documentation Page:

Iframe ?
Nav ?
or aside
which one should I use for the menu ?

Definitely not iframe. Semantically nav works better, but not because it’s the best choice, rather because aside is much worse… I would just go with div.

( trying to make similar layout > Build a Technical Documentation Page !!

<head style="font-family:bold;"> Bitcoin Cash</head>

      <nav><a href="https://www.bitcoincash.org/faq.html" target="iframe_a">About</a><br>
        <a href="https://www.bitcoincash.org/start-here.html" target="iframe_a">Start Here</a><br>
        <a href="https://www.bitcoincash.org/wallets.html" target="iframe_a">Wallet</a><br>
        <a href="https://www.bitcoincash.org/graphics.html" target="iframe_a">Graphics</a><br>
        <a href="https://www.bitcoincash.org/services.html" target="iframe_a">Services</a><br>
        <a href="https://www.bitcoincash.org" target="iframe_a">Home</a></nav>
  <p>A better money, is a Digital currency that can be used by anyone, anywhere, anytime.

  <h2><iframe src="https://www.bitcoincash.org/faq.html" name="About"></iframe><br>
    <iframe src="https://www.bitcoincash.org/start-here.html" name="Start Here"></iframe><br>
    <iframe src="https://www.bitcoincash.org/wallets.html" name="Wallet"></iframe><br>
    <iframe src="https://www.bitcoincash.org/graphics.html" name="Graphics"></iframe><br>
    <iframe src="https://www.bitcoincash.org/services.html" name="Services"></iframe><br>
    <iframe src="https://www.bitcoincash.org" name="Home"></iframe></h2><br>


I also don’t know much but the aside should be nav because it’s for navigating the page the height should be 100vh
That’s the value for the device height or viewport also it Should be fixed so it’s always visible
Then make the width take just the enough to display it’s content that is the navigation< a > text <
Then the rest should take the remaining width with a relative positioning to prevent overlapping
Hope this helps