Honestly your grammar's not that bad, I've seen much worse. Most CSS code doesn't work within the posts but they keep adding to the HTML5 support.

My favorite resource for HTML tags. A lot of these don't work here but the more basic and popular ones do.

Look here for Unicode symbols.All you have to do is click on the symbol you want copy and paste the html code it gives you and boom, your done!

Looks like you already know the H1 tags.

Bold
<b>text</b>
Italic (emphasize)
<em>text</em>
Super Text (can be stacked)
<sup>Text</sup>
Strike-out
<del>text</del>
Paragraph 
<p>text</p>
Anchor tag (text link)
<a href="Website Address Goes here">text for the link goes here</a>
Images
<img alt="Image description for search engines" src="http://www.YourImageLink.here" />

I hope this helps. Welcome to Steemit!