How to use my own image for my UI Slider's Background

Hi guys. Could someone help me?

I created a curved slider and put it in my Sprites folder. Now I drag into the Slider’s background Source Image and It doesn’t work. I try clicking on the little circle to access the menu but my image is not there too.

What am I missing?

Make sure that the image is a sprite. You can do that by selecting the image, going to texture type and selecting sprite. Otherwise I’m not sure what it could be.

Thanks guys. Wasn’t aware of this.