To get a character, you normally would have to join a game and the GM assigns you a blank sheet. There are solo games out there (one GM and one Player) but no GMless solo games like some video games that I know of. Considering that the hobby is a based off a social aspect, it is hard to find those solo games. Have you thought about text based games where you can post when you have time? There are many text based gamers and text based games on roll20.