Edsby provides a good article on the basic steps required for importing grades to the Edsby gradebook here: https://edsby.com/help/gradebook-2-3/gradebook-importing-grades/
What the article doesn't address, though, is the required format for the import file. There are three critical details:
1) All data needs to be arranged in columns, with column headers in row 1. Each row provides the details for a single student for a single assignment. If you are importing results for multiple assignments, students will have multiple rows in the sheet - one row for each assignment that is being imported.
2) Dates are required to be in the format: YYYY-MM-DD or YYYY/MM/DD. The commonly-used formats for North America, with year at the end of the string, will not be recognized properly.
3) The file must be saved as a comma-separated value (CSV) file