how to farm with only 1 pc

well i heard the only way was by using this virtualbox thingy, but i have absolutely no idea how to set it up so i'm a askin, plz can anyone make a video or some kind of tutorial for how to set up and use this program?

i could set it up but i cant get my internet working on the virtual pc so ....
but you can ask your friends and farm with them

technically i cant do that, no one in my clan owns 2 pc's i do but only 1 is powerful enough to run the game.