OK, so what you need to do is assign one or more categories to your posts. You can create different categories by going to Posts > Categories from the admin dashboard. Let’s say, for example, that you create a category called Apparel, one called Furniture, and another called Food.
Once you’ve created your categories, then you would assign a category to each post. If you go edit a post, you’ll see a section called Categories in the right column. Uncheck the uncategorized category and check the appropriate category for that post. You can choose multiple categories if the post falls into more than one category. Click the Update button.
Finally, you’ll want to display all the posts which have the same category. Go to Appearance > Menus from the admin dashboard. On the left column should be a section labeled Categories. If you don’t see it, then click on the Screen Options tab in the upper right corner of the page. Mark the Categories checkbox and that section should now appear in the left column.
Expand the Categories section on the left, check off the Category that you want to add to the menu, and click the Add to Menu button. A menu item for the category should now appear in the section labeled Menu Structure. Drag the new category menu item to it’s appropriate place in the menu, e.g., under the Campaigns menu item. Make sure to indent the category menu item so it’s a submenu of Campaigns.
Click the Save Menu button, and now you should have a submenu item under Campaigns that will display posts from that category on a page (you don’t have to code the new page, WordPress will generate it using the index.php file, unless you’ve created a special template).
