SEQUENCE primary key

Hello

I have a question, if I have a table with a SEQUENCE primary key, that
obviously, I doesn't give in each new row inserted. For example if the
table locks:
CREATE SEQUENCE id_seq;
CREATE TABLE table (
id integer DEFAULT nextval('id_seq') CONSTRAINT table_id
PRIMARY KEY,
arg1 integer,
arg2 integer
)

How can I know which id receive each new row. I mean,
<http://ultralingua.com/onlinedictionary/index.html?action=define&ignoreaccents=on&wholewords=on&searchtype=stemming&text=sudden&service=english2spanish>
suddenly I insert one row (*) with the arg1 and arg2 . So ..., there
are something that I receive back ?? Some pointer, something? There are
any way to know which number receive my row ?

Thank you,
Gustavo

(*) This process can be multi-thread. In my case I use the libraries
with the wxWidget project with the class wxDbTable.