To build your columns "from scratch" you now you need to copy and paste the following code into your test site if you have created one. I wouldn't advise using your published site unless you feel confident enough to do so.
<div class="columns">
<div class="column"></div>
<div class="column"></div>
<div class="column"></div>
<div class="column"></div>
</div>
This is a four column grid, once you have copied and pasted it into your site, you can increase the number of columns by copying and pasting. For example, if you need a six column grid, copy and paste two of the code and place it above the </div> tag. Just make sure they don't exceed the width of the main body area, as if they do the last column will automatically turn over to the next row.
To reduce the number of columns just delete the code not required. Once you have determined the number of columns required, you can then copy and paste the whole of the code for the number of rows required.
I just looked at this training and it looks way over my head as you predicted, but that may be because I have not looked at the "creating a HTML grid" training yet. So I'll look at that and then come back to this. Thanks!
~ Rae Anne