How to change the picture for a D&D 5E Monster Manual Entry

I want to drag the Mage from the Monster Manual to my map and have the token loaded to the map and the character sheet loaded to the journal. So far this is all happening perfectly. Then, I want to use a custom image for the Mage token because I don't like the default mage image.  How do I use a custom image for the Mage token?  Once more I apologize for the noob-ness of this question! 

You can edit the entry once it’s in the Journal and replace the token picture that way. Sorry if that’s not clear...

Once you have dragged the monster into your game (it is listed on your journal tab), you can edit it to your heart's content. To assign a new token, c heck the steps on  this page  or  this video .

Thanks for the help!! This is a great program, but the depth of options means there's a lot to learn!!