1. Open a command console and go to the directory where you installed Postgre server.

e.g. D:\Program Files\PostgreSQL\9.3\bin>

2. Drill down into BIN folder and issue following command.

psql -d <database name> -U <username>

3. Issue  CREATE EXTENSION command to import extension

CREATE EXTENSION "uuid-ossp" ;

NOTICE: There is a semicolon at the end of command.

4. After above steps, you can check if the extension has been imported successfully by calling following command.

 select * from pg_extension;

5. If succeed, you should be able to see the list as below.

extname  | extowner | extnamespace | extrelocatable | extversion | extconfig | extcondition

-----------+----------+--------------+----------------+------------+-----------+--------------

 plpgsql   |       10 |           11 | f              | 1.0        |           |

 uuid-ossp |    89286 |         2200 | t              | 1.0        |           |

6. Now, you may generate UUID by uuid_generate_v4()

select uuid_generate_v4() ;