Chances are, your computer has a graphics card that was made by either nVidia (an nVidia GeForce graphics card) or AMD (an ATI Radeon graphics card). Depending on who made your graphic card, you'll want to go to their respective website (nVidia:
http://www.nvidia.com/content/global/global.php or AMD:
http://www.amd.com/Pages/AMDWorldwide.aspx) and find the DRIVERS (usually listed under "Driver Downloads"). Drivers are pieces of software that help your graphics card work properly. Download whichever driver was released most recently for your 3D graphics card. Install it, restart your computer, and try playing Legions again, to see if the issue is still there!
Also, what is your native language? There might be someone on the forums who is bilingual and will be able to explain this all to you in your tongue. =)