trying to put a leaf on a plane but ue4 trys to put a background on the picture how do I remove it?(the picture itself does not have a white background)
If you have photo editing experience the correct way is to take your original image to photoshop, turn the leaf white, and make the background black. Merge them, and hit ctrl d to select the merged layer than hit ctrl c to copy it. Then go to channels create a alpha channel and paste that into it. Re export your texture as a png and use the alpha channel as the mask in the opacity channel of the material. The dirty way to do it is to go to any photo editing program make a black background, and turn the leaf white, and export as a jpg and just use that as the mask for opacity.
Basically your masking out the white stuff your seeing so you just see the leaf it has to be read as opacity. Also make sure you are using there foliage setting since its a leaf in the material:)