You can drag and drop portlets onto pages in the WebLogic Workshop Platform Edition Portal Designer.
The vertical or horizontal placement of portlets in a placeholder is determined by the selected layout for the page.
When you add a portlet to a page in the Portal Designer, a reference to that portlet is added to the .portal file. The .portal file is a template that can be used to create desktops in the WebLogic Administration Portal. When a portal administrator creates a desktop based on that .portal template, the portlet is added to the portal resource library where it can be added to pages in streaming desktops. See Single File vs. Streamed Rendering.
For details in adding a portlet to a portal desktop in the WebLogic Administration Portal, see Add a Portlet to a Page in the WebLogic Administration Portal Online Help on e-docs.
The Portal Samples contain sample portlets that you can reuse in your own portals.