The toolbar above the text box is pretty self explanatory for most things. Bold and italics are the B and I. You can either highlight the text you want and then click the button, or click the button to enter the modifiers (or just type them in yourself.)

The chain is for making links, text first in the square brackets, url second in the parentheses.

Smiley is emoji (we have the best emoji, folks.) Sometimes our custom emoji are slow to load, just give them time.

The picture of the mountain and sun is for uploading images (you can also generally paste images in.)

The H is for headings, which would make the line have big text. This hasn't worked for me since at least the couple of updates leading up to federation, the system that allows us to interact with posts on lemmygrad and other instances.

Strikethrough is the S with the line through it, you seem to have figured that out! Nice! Works similarly to bold and italics.

The quotation mark allows you to do...

This. Pretty useful for replying to a specific part of someone's post.

You can use a hyphen to make a bulleted list like so:

• pig
• poop
• balls

Make sure you put a space between the hyphen and the text you want bulleted. Also make sure to hit enter twice to break up your lines, otherwise they won't actually separate.

tick marks ( use the <> button) allow you to write in monospaced font like this without formatting, useful for code or other situations.

The ~subscript~ and ^superscript^ buttons which look like x'es with a little text cursor down or up, allow you to make small text low or high. Also handy for math stuff. 6^9^

The triangle with the exclamation point is for spoilers or other collapsed text.

Don't click the question mark in the circle or it will delete your post and take you to the help page.

Also you can use a backslash (\ this guy) as an escape character to be able to post a modifier character, like so: ^

I recommend hitting the preview button before posting just to double check that everything worked right.

[ put the text you want here ] ( put the URL here )

Do that without the spaces between the brackets and the text to make your hyperlink.

For quotes, start each paragraph with a >

But if you want the vertical line to not have breaks

like this

then you also need to put a > between the paragraphs

like so

Also, you can see what someone typed to make their comment. One of the buttons on other people’s comments looks like a little text document (on mobile you have to click the three vertical dots to see it, I forget where it is on desktop). Next time you see a comment and you want to know how they did that, just click that button.