Create A Sequence For Primary Key To Simply Auto-increment By Default Of 1

I'm trying to create a sequence for a primary key to simply auto-increment by the default of 1. I have a sql script written to generate mt tables, and I'm not sure how to modify the script to include the sequence. I also just want the sequence for a specific column, ie, PK, not the PK in all tables.

Here's a snippet from my script:

create table image
(
image_id int NOT NULL,
source_id int NOT NULL,
CONSTRAINT image_id_pk PRIMARY KEY (image_id),
CONSTRAINT fk_source_id FOREIGN KEY (source_id) REFERENCES source(source_id)
);

Would I add the create sequence statement right after the create table, and if so, how do I apply the sequence to only 1 table and a single column?