Can't select object in edit mode So I am a beginner in blender and trying to make a tree with sapling tool. I made it, added texture on leaves and I wanted to do the same to the bark but I faced a problem. When I want to select bark in edit mode to unwrap it, I can't. I only see these particles, these threads. 
Do you have an idea how to transform the bark into an object and unwrap it?
The tree's bark is a beveled curve, not a mesh object. You have to convert it first. Select the tree in object mode and hit alt+c then select curve to mesh. After you can unwrap it.