The first step is to select the spa in the spa selector, it will automatically load all the spas you have.
Then you choose the XLSX file to load.
Once loaded you will have a selector for each header in the excel
Here you will map the Excel headers with the corresponding Bitrix fields
When u select a field it will show
When you select a field it will show you the available options to avoid errors when importing
For the company or user fields you must put the exact same name as it is in bitrix