Owange's Autumn Overlay is built to sit on top of another texture pack. It recolors leaves, grass and plants to autumn shades and leaves the rest of your main pack's look alone. Load order is what makes this work.
Setting the pack order
1. From the title screen or the pause menu, open Options > Resource Packs.
2. In the Available column, hover over your main texture pack and click the arrow to move it into Selected.
3. Do the same for the Autumn Overlay.
4. In the Selected column, packs higher in the list take priority. Use the up and down arrows so the Autumn Overlay sits above your main pack.
5.
Checking that it worked
Load a world and walk to a forest or a grassy area. You should see:
- Leaves, grass and plants in warm yellows, oranges and reds.
- The same block shapes and designs your main pack gives them. Only the colors should change.
- Everything else, such as stone, wood and buildings, still looking exactly like your main pack.
If the shapes of leaves or plants suddenly look like vanilla Minecraft, your main pack is probably not active. Make sure it is still in the Selected column underneath the overlay.
Switching seasons: To go back to green foliage, open the Resource Packs menu and move the overlay back to Available. Your main pack stays selected, so you can swap between autumn and summer whenever you like.