Editing your WordPress menu is TOTALLY something you can handle yourself, no need to learn to code or hire someone. There’s a video and written instructions below and you’ll see how easy it is to add pages, categories, sub-menus (drop downs), blog posts, and even links to your menu.

How to edit a WordPress menu:

Open the menu page by going to Appearance > Menus.
Select a menu to edit.
This appears in a drop-down box selection if more than one menu was previously created. Pick one and click the Select button. The menu items will be displayed.
Add a menu item.
To add a menu item, you can choose from Pages found in the Add menu items section. It will show three tabs:
a. Most Recent
b. View All
c. Search

Place a check mark beside the item(s) and click the Add to Menu button. The item(s) will be added in the menu list.

Can a post be added as a menu item? Definitely. Click Posts in the Add menu items section and you can select from Most Recent or View All tabs. You can also look for a specific post by going to the Search tab. It will pull up the post you are looking for. Check that and add to the menu list.
Add a sub-menu item.
You can add an item as a sub-menu by sliding the item to the right. You will see an outline at the back of the box you are dragging to guide you where it will go.

Slide the box within that outline and you will see it become a sub-item. Keep sliding and you will be able to create a sub-sub-item.
Add a non-linked menu item.
You can also add an item that you don’t want to have a link to. This is usually done when you have a main item like the About page. This can have two sub-items such as About Me and About the Blog.

Use Custom Links found in the Add menu items section. Add a hashtag in the URL and provide the text for this link.