Hulldo teaches you how to draw lined paper in GIMP. First you create a new document and make it 600x600 pixels. Make the background a bluish grey. Create a rectangle in the middle of the document. Now you want to add a blue horizontal line. You will want to then duplicate that layer until you're at the bottom. You can add a stroke to the rectangle or use a shadow to make it look like it's on top of a regular piece of paper. You also have to leave some space at the top and bottom to mimic a real piece of lined paper.