im having trouble with the site im makeing, i have a lits for the table of contents (a long list) and i was wondering if anyone knew how to change the list from this

<ol>
<li>hi
<li>hi again
<ul>
<li>hello
<li>how are you
</ul>
<li>this is the end almost
<ul>
<li>yes
</ul>
</ol>
change so it looks like

<ol>
<li>hi
<li>hi again
<li>this is almost the end
</ol>

but when you click on "hi again" it will bring down the others (hello, how are you) below it. i hope you understand what im saying