To add actuals to a manual entry field (that is, when the actuals are not coming from your linked sales or accounting system), go to Load Data>Manual Entry (left sidebar), and add data for the relevant time period.
Use the three dots to rename or remove a line.
To add a new manual entry field, see How can I add a new field for manual entry? How can I add extra data and/or non financial data to ScaleXP?