There is a small shortcut method for hiding file in JPEG
For small documents this method is crucial:
1. Gather your image and the files you wish to lodge into it. Here I have a main.txt which I will hide inside my Flower.jpg.

2. Add the files you want to hide into a new RAR archive. (so main.txt.rar created newly)

3. Open Command Prompt and go to the folder where your files are located, e.g., 'C:\Secret'.

4. At command prompt type "copy /b flower.jpg + main.txt.rar technary.jpg" (without quotes). (flower.jpg is the picture I want to show, main.txt.rar is the file to be hidden, and technary.jpg is the file which contains both).

5. Now test the technary.jpg by double clicking it, and verifying it still opens.

6. Now try opening that same technary.jpg file from menu: file->open of WinRar. It will show the original hidden file Main.txt.

Now technary.jpg is a simple JPEG for others, but it contains a secret file main.txt for you!

Please Note: You can change the file names as per your needs. the technary.jpg was just an example file and you can create and name as you want!