If you are talking about lyme disease then it is not a virus, it's a group of bacteriums named borrelia that causes it. Its a zoonosis which basically means that the bacteria is transmitted via animals, lyme disease are often tick-borne.
Several different ways. Through air, sneezing or coughing, sexual transmission, mother to child, blood borne and so on. There are many ways, depends on which virus you want to study, how they look like, what celltypes they infect and which environments they prefer.