You can create a new file by selecting the "+ New" option in the Odoo admin header, directly from the front-end. And choose the "page" option.

You can save (or rather export) your files by selecting the green "export" button in the top right navigation menu. Then you have to choose the option "save as pdf" in the print view of your browser (instead of a printer). In theory, you can print directly to a printer, but only for testing purposes.

Don't worry, they won't appear in the exported version of your files!
The green line is the recommended content limit area, if your content exceeds this area, you may have problems when printing. It is allowed to go a little over on the bottom area.
The red line is the cut zone, if your content goes beyond it, it will be cut off when it is printed! Never go beyond it.

For the moment, the files are exported in A5 format, with bleed and cut lines. A variation can be added in the future for certain documents.

To avoid breaking the builder, only custom snippets are available in the editing function. 
These snippets are optimized to avoid going outside the guidelines of the instruction cards.

Firefox for exporting