To iconify a window, move the mouse cursor to the little boxed "X" in the upper left corner of the window. The cursor will change into a pointing finger. Click the left mouse button and the window will close up and an icon for it will appear at the edge of the root window.
To move a window, move the mouse cursor to the shaded strip at the top of the window (the title bar). The cursor should change to an arrow. Press the left mouse button and hold it down while you move the mouse to change to position of the window. When the window is where you want it, release the button.
If you have more than one window open, they might be positioned so that the window on top hides part of the window underneath. To bring the bottom window up the the top, put the mouse cursor in the title bar and click the middle mouse button.
To change the size of a window, place the mouse cursor in the box at the upper right corner (the one that looks like 3 boxes, one on top of the other) and press any mouse button. The cursor will change to look like a four arrows and a box will appear in the upper left corner of the display which shows the size of the window (number of columns and lines). While holding the button down, move the mouse around until the window is the desired size and then release the button. You have to touch an edge of the window with the cursor in order to move that edge.