By definition, you will have no order in a DB unless you put it in there. So it will be absolutely uniteresting, where the row will be inseted into your table.
You need to put a field into your table, which helps to sort your rows. I would use a field with type "serial" which is incremented for each entry. A nother possibility is to use a field with the type "timestamp".
To get the entrys out of your db, you just use "order by" to get them in the right order.
It is absolutely uniterestinf, if there is one number missing in your order (when you have deleted a entry).
If your sort field was "sort", the whole thing would look like :
select * from table order by sort;
