How to add a Web Part Zone on a page?

Open the Page in SharePoint Designer.

1. Open Web Parts task pane: click Task Panes --> Web Parts.
2. Click at the location on the page where you want to insert new web part zone.
3. Click “New Web Part Zone” at the bottom of Web Part task pane.
4. Right click on new web part --> Web Part Properties
5. Edit properties if required --> Ok

(Refresh page in IE to see the changes)