To dynamically add content to a web page, you need to create new elements and insert them into the DOM. JavaScript provides the document.createElement method to create a new element node of a specified type, such as "li" for a list item or "div" for a division. Once you have created the element, you can set its properties, such as its text content or attributes, before adding it to the document.

To add a new element to the DOM tree, you commonly use appendChild or insertBefore:

• Use the appendChild method to add the new node as the last child of a specified parent node;
• Use the insertBefore method if you want to insert the new element at a specific position before another child. This requires the new node and a reference node (the node before which the new node will be inserted).

This process allows you to build lists, menus, or any other dynamic content based on user actions or data, making your pages interactive and responsive.