Ok, here’s a little of everything.
Go to “appearance” then “menus”
This will bring you to the place where you can add pages AND catagories to your top menu.
Be sure you select “catagories” and put them in your menu.
Embedding Other Stuff
There is a LOT of stuff online you can embed.
Let’s embed a tweet.
Select a tweet, and go to “more,” then “embed tweet.”
…and copy the code.
Drop it into your blog. REMEMBER to put a page break <p> before and after each tweet, to space it properly.
Some stuff has WordPress specific code…for example, Soundcloud.