How can I make animated background image?

I created a simple game and I have a main menu. For the main menu I am using a canvas and as a background an image (Sprite 2D). I want to that background to add an effect like animation. I am not sure if it has to be animated or particle system or something else. I am using Uniyt 5.5.4 and I have tried gif but it didn’t worked. I have read some questions about the topic and I found out that Unity does not support gif files.

Explanation:
I want the background to be my image without changes and I want smoke effect to be visible and moving. For example, smoke that starts from bottom of the screen and moves upwards.

See gif: Microsoft OneDrive

I want to know if I can manage something like this. Please give me any advice, book or link that I can read.

just create an animation clip, you just need an image as background and in the animation clip (animation window) change the property Image.image, and just loop it.