How do you make a virtual world for free

well, virtual worlds are very complicated to create:

if you are a beginner then the best platforms to get started on would be

xtremeworlds
eclipse
mmorpg maker xp ( currently not letting any one register )

these are all free


apart from those ones there are many other makers you could get
because if you look on you tube you will find many ways of making one like on game maker .