Answer 1

You have to form a <nav>-list inside your <header></header>.

For example:
...
<header>
<nav>
<ul>
<li>Home</>
<li>About Us</>
</ul>
</nav>
</header>

It will look like this
• Home
• About Us

You can add additionally - style="list-style:none;" to <ul> so the bullets disappear. And also "display:inline;" so that the list would appear next to each other.
>> <ul style="list-style:none; display:inline;">
__________________________
The whole magic:
...
<header>
<nav>
<ul style="list-style:none; display:inline;">
<li>Home</>
<li>About Us</>
</ul>
</nav>
</header>
...

It will look like this now:
Home About Us