Learn about importing multiple files.
Only one general ledger file can be imported per year, per analysis. You must combine the data into one Excel file on a single sheet, or one single text/CSV file.
If your files are all in otherwise ingestible format, you may use the Merge Action tool to combine them. If you also need to combine worksheets in an Excel workbook, you will first need to use the Split Action to split the sheets into individual files, and then you will be able to select which of these you would like to combine.
If your files also need to be formatted in addition to combined, you can submit a Data Formatting Request.