printing or exporting to PDF by inches instead of pixels

[RickCheney]

I would like to print or export the map that is on my computer screen to a size that will fit on the paper size that I choose.   For example, on my screen the map is a rectangle that is twice as wide as it is tall (think of a paper size that is 20 inches wide and 10 inches tall).

When I print to PDF, I can choose a custom paper size that is 21 inches wide and 11 inches tall, but when I try to print to PDF only a portion of the map prints, the sides are usually cut-off in the PDF.  

When I try to Export to PDF there is an Image Size which is in pixels.  I don't know how to translate pixels to the PDF paper size.

Any help is greatly appreciated.  If you have any questions, let me know.

[Luke_Pinner]

Add your map to a layout that is your desired dimensions?

https://pro.arcgis.com/en/pro-app/latest/get-started/add-maps-to-a-layout.htm

[RickCheney · Accepted solution]

Thank you Luke! That worked perfectly!  I tried following the step by step instructions and that was helpful but I needed to watch the video closely to understand.  The thing that I didn't understand was drawing the map frame into the layout automatically added the map to the layout.  I thought I had to import a map and when I did that it always opened a separate tab along the top.  Also, activating the layout and then un-activating it.