Only difference from your usual INSERT statement is that you add database (and schema) prefix.
INSERT INTO [Database1].[schema_Name].[TableXYZ]
SELECT
Column1
, Column2
, Column3
....
, ColumnN
FROM [Database2].[schema_Name].[TableXYZ]
INSERT INTO [Database1].[dbo].[tbl_empaddress]
SELECT empid, Address
FROM [Database2].[dbo].[tbl_empaddress]