Python script to automate reddit posts

redditr.py

import time

import praw


USERNAME = ""
PASSWORD = ""
CLIENT_ID = ""
CLIENT_SECRET = ""

TITLE = None
URL = None


SUBREDDITS = [
    # "python",
    # "django",
    # "webdev",
    # "programming",
    # "golang",
    # "datascience",
]


class Reddit:
    def __init__(self, config):
        self.reddit = praw.Reddit(
            client_id=config["CLIENT_ID"],
            client_secret=config["CLIENT_SECRET"],
            username=config["USERNAME"],
            password=config["PASSWORD"],
            user_agent="Script by u/wtfox",
        )

    def post(self, subreddit, title, url=None, text=""):
        if url:
            submission = self.reddit.subreddit(subreddit).submit(title=title, url=url)
        else:
            submission = self.reddit.subreddit(subreddit).submit(
                title=title, selftext=text
            )
        return submission


def main():
    assert TITLE is not None
    assert URL is not None

    config = {
        "CLIENT_ID": CLIENT_ID,
        "CLIENT_SECRET": CLIENT_SECRET,
        "USERNAME": USERNAME,
        "PASSWORD": PASSWORD,
    }

    reddit = Reddit(config)
    for subreddit in SUBREDDITS:
        print(f"Posting to {subreddit}:\n{TITLE}\n{URL}\n\n")
        sub = reddit.post(subreddit, title=TITLE, url=URL)
        time.sleep(1)


if __name__ == "__main__":
    main()

this is a little confusing what values do i need to change

It would be very helpful if you wrote some comments about what the blocks of code, the classes, the functions/methods and the loops do.