How to set auto-increment manually, so that a column that increments automatically will be create (4325763)

How  is  auto-increment set manually, so that a column that increments automatically will be created in a PostgreSQL database?

RESOLUTION 1:
1. Select data type "Serial" or "BigSerial" for a particular attribute.  
2. Generate the DDL script and use it in your database.    
3. In the database, PostgreSQL will  automatically create a sequence and will relate to the attribute  by default.

RESOLUTION 2:
Set  manually in Toad Data Modeler what PostgreSQL can do automatically (e.g.  as  described in previous option).
1.  Create a sequence, e.g. Sequence1. - Model Explorer | right-click the Sequences | Add.
2. Edit the particular attribute and in the  'Default' field, write the following: nextval('Sequence1').

Please Note: If you wish to make the sequence dependent on entity/attribute (which means that if  the entity/attribute is deleted, the sequence will be deleted too), edit the sequence and on the 'General' tab, fill out the "Owned By" box. However, for basic functionality of auto-increment, this is not necessary.

If you add a primary key to an attribute, there is no  need to  select the 'Unique' checkbox  and  set it to an alternate key. The Primary key is automatically unique.