Imagines

Well just make sure about a few things first
Lets assume you are creating your html project in a folder called Demo and you have your main html file called main.html in the same folder demo.
In the same folder you have your image file called image.jpg
So to call your image i.e. image.jpg in your main.html file you will use the tag

<img src="image.jpg" alt="alt_text" />

If you have your image files in a subfolder called images inside your Demo folder then you will refer to the image as given below. Subsequently add the preceding parent folders name in front of the child, followed by a forward slash / if your image files are two or three folders deep

<img src="images/image.jpg" alt="alt_text" />

// OR if your images are stored in a deeper level of folder structure then use this notation
<img src="parent_folder/child_folder/images/image.jpg" alt="alt_text" />

Try looking into your html code too. Maybe you spelt something wrong (it is case sensitive) or forgot to close the tags.
If it still doesn't work you can post your code here so that we can look into it.
Hope it helps