Screen size

The screen above is probably what your desktop looks like. While on the desktop, push the right mouse button down and release it. You will get the box of selections shown below.
Highlight the selection called properties. Then click on it with the left mouse button. You will get the window shown below.
You will note in the upper right hand corner a tab that says "settings". With your left mouse button, click on the settings tab.
Once you have selected the "settings" tab, the window below will open. Notice in the lower right corner a slide bar with the title "screen area". Move the slide to the desired resolution. Most web pages are displayed at 800X600 pixels. This page is set up for that.
In the lower right corner is the apply button. Press the apply button and you will be asked if you want to change the settings just select yes. Another window will open with the changes and you will be asked again if these changes are ok with you. Just select "yes". When you come back to the window above, press the "ok" button and you're in business.