Help me get started with moving away from Firebird

I was able to create all the domains, tables, views, etc, but I have trouble creating stored procedures and triggers. Also, a question, does Postgres support events, for example in Firebird I could do something like this and then receive the event in the GUI:

  if ((NEW.MUSED_M_>=NEW.MLIMIT_M_) and (NEW.MLIMIT_M_>0) and (NEW.ISACTIVE=1) and (NEW.FAXTOFAXFLAG=1)) then
  begin
    POST_EVENT 'deactivate_f2f';
  end

Please help me translate the examples bellow so I can understand the differences:

CREATE GENERATOR GENADMINID START WITH 0 INCREMENT BY 1;
SET GENERATOR GENADMINID TO 108;

CREATE TRIGGER B_UPDATE_COMPANY FOR COMPANY
ACTIVE AFTER UPDATE POSITION 10
AS
begin
  if (old.AGENTID != new.AGENTID) then
  begin
    update USERS set USERS.AGENTID=new.AGENTID where USERS.COMPANYID = new.COMPANYID;
  end
end

CREATE PROCEDURE GET_ATA_STATUS (
    MAC VARCHAR(128),
    NOW_D_ INTEGER)
RETURNS (
    ATA_STATUS INTEGER)
AS
begin
  SELECT IIF((a.TIMESTAMP_D_ + a.EXPIRE) > :NOW_D_, 1, 0) FROM ATA a WHERE a.ATAMAC = :MAC into :ATA_STATUS;
  SUSPEND;
end

Thanks a lot.