Hi,
If you right-click on your table in your Table of Contents and select 'edit features' -> start editing.
if you now right-click and open up the 'attribute table' you will see your records.
scroll to the bottom of this table and there will be a blank row in which you can double-click and insert your data.
be aware this will not take on any location at this point. if you are adding this as xy data you may be best to edit the table outside of arcmap and import as xy data.
