So I've been trying to import an item from blender into Roblox, all textured.
It looks like this in Blender, which is what I'd want: https://i.imgur.com/KttvCFb.png/
However, when I open it up in Roblox, it looks like this: https://i.imgur.com/gDzAyPf.png
Any help would be appreciated, thanks. I'm basically making it look like it is in Blender with two colours, not just one.
This happened with me too, just look up how to texture bake on YouTube. That will be sure to fix your problem, as it worked for me.
You will have to create two separate meshes - one for the tree stump at the bottom and one for the leaves for the top.
The way you've coloured in your tree in blender is what you desire and is correct - but keep in mind that Roblox treats that one tree as one part, not two parts so that's why the tree you inserted into Roblox is all green instead of two colours (green + brown)
Hope this helps.