Bappity Rabbity  depending on the type of coding your doing, the googlefont will look different but you can place it within the body of the code! (so not the style-sheet!).

for bbcodes (like on proboards) it would be formatted as follows:
[Googlefont=The+Font]
but for HTML, it will be something like this
<link href="https://fonts.googleapis.com/css?family=Asap:700&display=swap" rel="stylesheet">
now newclass tags, to my knowledge, are for bbcodes (i could be wrong, i am only saying this because i've only ever seen newclass used on proboards which i know uses bbcode). i believe that the newclass style tags require the Style Tags plugin in order to work properly on a proboards website.

i'll write out a style tag as i normally would in HTML & CSS, and then convert it to a newclass style tag as an example:
.myclass {
font-family:The Font;
font-size:10px;
color:#000;
}
and now in newclass,
[newclass=.myclass]font-family:The Font;font-size:10px;color:#000;[/newclass]
in my experience it has been very important in newclass tags to have them be one continuous line of code, otherwise they don't seem to work/translate into the body aspect of the code. another difference between newclass style tags & HTML/CSS is that CSS classes are always enclosed with the <style> </style> tags, whereas newclass is not enclosed by this tag. i personally don't know why but i'm sure there's a reason for this! 

another thing with newclass/bbcodes, is that you need to have the [*nospaces] (without asterisk) class somewhere within your code so that proboards/bbcodes doesn't automatically create a big long spaced-out code. i have forgotten this many a time and been like "what the--" when testing my codes, haha!

some other differences between the two:

•  break tags in HTML are <br> but in bbcode they are [*break] (without asterisk)
• < and > in HTML are [ and ] in bbcode
• the div classes are different, we'll go over that next!

so for HTML the div classes usually look like this:
<div class="myclass"> </div>
however in bbcode they look like this:
[div][attr="class","myclass"] [/div]
again, i don't know why this is, it just works.

thhaaaaat's about what i can remember in terms of the structure of each type of coding & how they differ from one another. learning how to code is genuinely a process of trial and error (or it has been for me), and while it may seem daunting, it's incredibly rewarding. here's a list of some websites where you can learn to code, but i have my own resources for expanding upon coding that i would be happy to share with you if you want to send me a pm! to practice coding you can create a free account on codepen or jsfiddle. i personally recommend w3schools for simple introductory coding tutorials. also, if i were you i would focus on learning HTML & CSS first before dabbling in anything to do with javascript/jquery because that stuff can get really confusing and difficult (i honestly have a lot of trouble with it myself). 

hope this helped! if anyone wants to elaborate or add, please feel free! i'm sure i've missed things! xx