That "A" with the little arrow is your fonts. All of your fonts will 
be listed there for you to choose from. 
Nothing to install! :D 

Click 'add more fonts'

You will see this panel next:

Fonts you install (by just simply clicking the little box to put a check mark)
- are listed on the right side. 

Every time I add more fonts, it shows me with a check mark
which ones I already have. 

We can change the drop downs at the top. I'm now looking in the 
category of 'handwritten' thats the style I like best. 

So when I find one I like. I just put a checkmark. And its added for me. 

See how I just added those 2 new ones. 

----------------------------

Lets have a look at the toolbar now. 

(kinda messy - sorry lol)

1. Undo
2. Re-Do
3. Fonts
4. Font Size
5. keep on normal I would say. but it contains special font sizing and formatting (paragraph, H1, H2...)

6. Bold Font
7. Italic Font
8. Underline Your Font (or title)
9. Line Through (or cross out)
10.  Font Color
11. Background color of post. I would not suggest ever using this one lol 

I didn't include the picture. But the next icon is the 'Link Anchor'. 
For linking text. 

Simply just drag your mouse across your word to highlight it. 
Click the link icon. 
And paste or type the URL you want your text to take your visitors to. 

I use that same method to change the font and size and color of my text 

when composing a post. 

Now wasn't this easier than you thought. 

(Amarant, Happy Monkey, Pangolin)