components base address and offsets

OK I did not get it, here is my components slave interface :

port ( clk : in std_logic;

resetn : in std_logic;

read : in std_logic;

write : in std_logic;

chipselect : in std_logic;

writedata : in std_logic_vector(15 downto 0);

byteenable : in std_logic_vector(1 downto 0);

address : in std_logic_vector(1 downto 0);

readdata : out std_logic_vector(15 downto 0);

SIG_EXT : out std_logic_vector(1 downto 0)

);

How do I write some data to the ""writedata"" pin ???