In the Toolbar tab you will have the option to set the icons you would like to use for each feature. You can choose to use the "Icon Theme" bar, which are preset icons for each feature. All you have to do is click on the one you would like to use and push the "Apply Theme" button.
If you choose to add your own icon, you will click the pencil to the right of the feature under "Active". From there you will have the option to upload your own icon. Make sure the size of your icon is compatible with the size requested.
Please be sure to hit "Save" after each action or else you will have to do it all over again. Also, you will want to publish.