After opening Tiled, select "New Map", a custom size measured in tiles and as tile size select 32x32 as this is the size the library currently supports.

Create a New Tileset

In the editor, go to the lower-right corner and select "New Tileset".

Give your tileset a name.

Make sure to select "Embed in map".

Choose your tilesheet as the source.

Draw Your Environment

Once imported, you can select tiles from the tileset and use them to build your environment.

Understand Layers in Tiled

Tiled allows you to use multiple layers for organizing your map.

You need to give your Layers seperate z-Indices to decide their rendering order, the lower the number the earlier it gets rendered.

In order to do this select a layer.

Add a new int property named "zIndex" and give it a number starting with 0 to decide when to render it (0 gets rendered first etc.).

Important: Tiles that should have collision must be placed on a separate layer.

Set Up Collision

Select the layer you want to have collision.

Right-click and go to "Custom Properties".

Add a new boolean property named "collision" and tick the checkbox.

Any tile placed on this layer will now automatically have collision—meaning moving entities cannot pass through them.