Custom Sidebar Icons
Open Template Page
Under the template (opens in a new tab) section the Tebex panel, click "edit".
Change Setting
Locate the "Use Image Icons on Sidebar Categories?" option and set it to "Yes". Then, click the "save and publish" button in the upper right.
Edit a Category
Head to the packages page (opens in a new tab). On a category, click the three small blue dots on the right, and then click edit.
Upload an Icon
On the right-hand side of the screen, upload an image you want to use. Ensure that the image is cropped to remove any white space on the sides and that the background is transparent. Once uploaded, click the "update" button at the bottom of the screen.