Either I don't understand your question or you have phrased it wrongly.

If you are attempting to insert multiple values at the same time,
do you know what you are trying to insert?

DO I know the value ahead of time?
If the value you are inserting is the same or an increment of a number
you can do that using a "for loop" Like :
For i in 1..10 Loop -- Do it 10 times
Insert into test_table (name) values ('Gram2000');

Are you trying to load values from another table?
if that is the case use :
Insert into test_table select username from all_users;

If you have all your data in a flat file, use sql loader. You can skip
sqlplus and you can also use direct path load which will make it
really fast.

Hope I am helping!