How to build a TRIGGER in POSTGERSQL

<br /><br /><p><font face="Arial" size="2">       Hi ,</font><p><font face="Arial" size="2">      I need some help in 
building trigger and information about sysdate (System date), any help will be appreciate.  </font><p><font
face="Arial"size="2">      1) I need to build a trigger that every time I insert into the table  one of the columns
will get +1 number.</font><p><font face="Arial" size="2">           I have it in ORACLE ( see below the create of the
sequenceand the trigger) but how you can do it in PostGer SQL) </font><p><font face="Arial" size="2">  </font><p><font
face="Arial"size="2">   CREATE SEQUENCE AD_MNG_SYS_SEQ MINVALUE 1 MAXVALUE 999999 CYCLE;</font><p><font face="Arial"
size="2">   CREATE TRIGGER AD_MNG_SYS_TRIG</font><br /><font face="Arial" size="2">    BEFORE INSERT ON
AD_MNG_SYS</font><br/><font face="Arial" size="2">   REFERENCING OLD AS OLD NEW AS NEW FOR EACH ROW</font><br /><font
face="Arial"size="2">   BEGIN</font><br /><font face="Arial" size="2">   Select AD_MNG_SYS_SEQ.NEXTVAL INTO :new.AMS_ID
FROMDual;</font><br /><font face="Arial" size="2">  END;</font><br /><font face="Arial" size="2">   /</font><br
/><p><fontface="Arial" size="2">        2) what is  equal to 'sysdate' (to get/put the system date in a table)  in
PostGerSQL.</font><br/><br /><p><font face="Arial" size="2">     Thanks,</font><p><font face="Arial" size="2">    
Ilan</font>