How to create those 2 transparent column?

1.Dont use Avada (it's an awful bloated and poorly responsive theme.

2. Create the boxes using divs and a bit of CSS. If you really really have to use Avada, create a child theme so your boxes don't get wiped if there is Athens update.

 

There are loads of tutorials on how to do the coding for this. Just search for side by side boxes/divs and CSS transparency. Chose the one you like and add it to your page/style sheet.

Avada is kind of lost and losing its shine. Probably they oversold it.

 

Well to make these two columns use the fusion editor column options. Then you will have to write custom css to enable the transparency and the shape.

I have no clue of writing code

Then get someone to do is for you. But anyone who will takes this on will strongly suggest you don't use Avada. It's a very difficult theme to modify