Create a new page called addchild.html.  Put this HTML inside the body element (under the main heading):

<p onmouseup="addMoreParagraphs();">Add more paragraphs by clicking here</p>

then put this JavaScript inside the script element:

function addMoreParagraphs() {
    var newElement=document.createElement('p');

Try it and a paragraph should be created with the lines of JavaScript doing this:

  1. create a new element (called newElement but it could have been called anything) of the type p (the element is created as a JavaScript object not in the page at this stage)
  2. change (add) the content of the element
  3. add the element to the page as a child of the body element

You can also add attributes to the element before creating it.  Add this line of code before the current appendChild line:

newElement.setAttribute('style', 'color:#D400D4');

The element now has in-line styles.  You could set a class, id or an event trigger in the same way.

You do not need to add the new element to body.  You can add it as a child to anything (maybe using getElementById).