You can add a row by passing Column Name-value pairs.
Click "+" button and select "Others ..." -> "Add Row Manually"
Select Column that you want to set a value.
Enter a value for the column in the Expression field.
Click "Run" to add a new row.
If you want to enter values for the other columns in the row, you can click "+Add New" on the "Add Row Manually" step.
Then repeat the same for the other columns, and you can add a row like the below screenshot.