Great start! Here's a cleaned-up/reformatted version, based on linting from black and isort:

#!/usr/bin/env python
# Evan Nguyen
import ctypes
import datetime
import os
import time
import urllib.request

import praw


def main():
    dir = os.path.dirname(os.path.realpath(__file__)) + "\\data\\"

    get_image(dir)


def get_image(directory):
    # initialize praw.ini
    reddit = praw.Reddit("bot", user_agent="reddit2desktop")
    get_hottest = reddit.subreddit("wallpapers").hot(limit=1)

    # obtain post info
    for post in get_hottest:
        url = post.url
        link = post.permalink
        title = post.title
        author = post.author.name
        date = datetime.datetime.fromtimestamp(post.created)

    # create directories
    dir = directory
    if not os.path.exists("data"):
        os.makedirs("data")
    image_directory = directory + "current_img.jpg"
    text_directory = directory + "info.txt"

    # retrieve url, download to the directory / output post info to txt file
    urllib.request.urlretrieve(url, image_directory)
    with open(text_directory, "w") as file:
        file.write(
            "Title: "
            + title
            + "\n"
            + "https://reddit.com"
            + link
            + "\n"
            + "Submitted by /u/"
            + author
            + " on "
            + str(date)
        )
    # set wallpaper
    SPI_SETDESKWALLPAPER = 20
    ctypes.windll.user32.SystemParametersInfoW(
        SPI_SETDESKWALLPAPER, 0, image_directory, 0
    )


if __name__ == "__main__":
    main()