I can’t get my full screen with my desktop and problems

Hello and thank you in advance!
I recently purchased Fortress F160TM Touchscreen Monitor 15.6". I am having issues getting its proper size. I haven’t done anything I just plugged it in to my desktop with Windows 8 operating system. What could’ve cost this issue? I tried to check the settings of my video card and checked the menu in the monitor screen but it seems I cannot get it resolved. Can anybody help me resolve this? Please provide me step by step on how to eliminate this. Thank you!
