Well, you're not really making it; Blender will make it for you. But now is a good time to briefly look at what is available.
Open up Blender, or select New from the File menu. You already have our first basic object, the cube.
Press Ctrl+MMB, and use the mouse to zoom in close to the cube, so that you can see it well.
Press the X key to delete the default cube.
Now, you can make a new object. Press the Shift key and the A key at the same time. The Add Object menu will pop up, as seen in the following screenshot. There are quite a few kinds of objects that you can add, from Meshes and Metaballs, through to Text or Cameras. So, to start by making a mesh object, move the cursor over Mesh, then select Plane with theLMB.
You just made a plane. It can be a building block for a larger object, used as the ground or the surface of the ocean.
Press the X key to delete the plane.
Press Shift+A to open up the Add menu, and select the circle. The circle has no face...