First, does your computer have both English and Hangeul characters on the keyboard? If so, to toggle between the two languages there should be a button on the bottom right next to your space bar button. On it it should say, alt and below that it should say 한/영. Click this button to toggle between the two language input options. If your computer does not have the two characters on your keyboard, then you should look at the taskbar (at the bottom of your computer screen) and if you right click here a window will open. In this window, scroll to the toolbars option and click on the language bar. Now there should be a collection of language options on your taskbar. Click on these to change between input languages (provided they are available on your computer).