1. To get up the Upload File connection method, you need to choose Upload File over there. 

2. Then, Click or Drop your file over the blue box there. 

The upload file has a limit of 35 MB. To process a bigger file, either upload the file to FTP and use the FTP connection method or zip the file.

3. File Format can be set to Auto where Stock Sync auto-detects the file format or the user can also choose the type of file format that they attaching for the connection method accordingly.
The File Format that can be set by the user is CSV, XML, XLS, XLSX, JSON, .TXT, EDI, and HTML Table.

If the uploaded file is compressed (.zip or .gz), then the file format must be chosen as Stock Sync doesn't auto-detect format in compressed files.

4. For the First Row Header, enabling the toggle icon it will help the feed file which had the first row as header, for example, SKU, Vendor, Description... 

5. Lastly, for the Sheet Name you can put the sheet name under that field. If there are multiple sheets separated, you can put a comma to separate them. 

For example Sheet1, Sheet2