If you have ever changed a screen saver on your computer, then this should not be too difficult for you. Right click on the desktop and a menu will pop up. From the menu, select either 'active desktop/customize' or 'properties' ( they both take you to the same place). Find the tab that says 'settings' and access it by clicking over top of it. Towards the botom right corner of the window you will see a slider bar. slide it to the desired display size ( in this case, 1024x768) and hit 'apply'. A message will appear informing you that you have changed your desktop display.
All this really does is make your icons appear slightly smaller on your screen, and gives you a whole lot more room to work with. This is a nice trick to use if the icons on your desktop are beginning to get too crowded (ie filling up half the visible screen)
If this method worked, then you're all ready to go. There is, however, one rather lengthier way do do the exact same thing. To change the size this alternate way, click on the start icon in the bottom left hand side of your screen. scrollup until you come to the settings panel and hover the mouse over it. From the pop out menu, choose control panels and click it. A screen will open up, with several small icons. Find the icon labeled 'display', and click it. This will access the display properties page, where you would set your screensaver. Find the 'settings' tab and click on it. At the bottom right hand corner of the page you will see a slider with the various numbers 800x600, 1024x768 etc. Move the slider over the desired resolution and click apply. A window will pop up informing you that you have changed your screen resolution.
Screen resolution simply tells you how many pixels (dots) your screen is going to display. The higher the numbers, the more crisp and smooth most graphics will look on the screen.
How to change your screen resolution