Create the basic Texture

First of all, we take some Images from a Texture site (CgTextures.com).
In this Example i use 6 different Images (2*Gras / 2*Rock / 2*Sand).
Now we open The GIMP and create a new Image wiht this properties (Picture#1).
Now we'll open the first Gras Image.
To make the Image seamless, you must select Filter -> abbilden -> Nahtlos machen (Picture#2)
Now we have a seamless Gras Texture, but if we fill this Texture in our Texture (Layer:Gras#1), well see that 
the Texture is to big scaled.
To scale the Texture down, we'll select Filter->Abbilden->kleine Kacheln(Picture#3).
Use this Properties(Picture#4).
Repeat this Steps for all Texture Images you'll want to use!
If this done, we select the Clone Tool and select a point in the Middle of the Gras Image (Press:STRG+LMB).
Now we stamp the whole Texture Image (Layer:Gras#1).
Now it must be Look like this.(Picture#5)

Create the "Rocky Part"

In the next Step, we will create the Base Rock Part.
Select your "Rock" Image , align the Clone Tool in the Middle and fill the Texture (Layer:Rock#1) into your Texture Image.
Maybe it could be Looks like this(Picture#1).
In the next Step, we paint the other Rock Image over the First one (Layer:Rock#2).
Now it looks like this (Picture#2).
To make this a little bit better, select the Rubber Tool and delete some little edges of the Shape (Layer:Rock#1) and 
paint some Gras on the Rocks (Layer:Rock#2)
Here the Result (Picture#3).

Create the Path

In this Step, we take the Stamp Tool again and paint the shape of a Path on the Texture (Layer:Sand#1).
Now it Looks like this (Picture#1).
To make this path more interesting, we paint a "Outline" on the Path. (Picture#2).
Now the last Step, paint a small line nearly the Middle of the Path.(Layer:Sand#3) (Picture#3)

Finishing
In the Last Step we paint on the second Gras Layer to make the scene looks more various.
And here is the Finish Result: