i used to alter jean skirts for myself, cuz im short and skirts are usually too long for me. So, what i did was i'd use scissors to cut the skirt to the right length, then just put it into the washing machine, and TA DA, a nice short jean skirt with a frayed bottom! But, what u might want to do is after u cut the jeans with the scissors, use a sewing machine to just sew slightly above the cut so that the fray will go up to the point where u sewed... or else if u wach the jean too many times the fray might move up and up.. do u get wat i mean?
anyway, hope i helped!
anyway, hope i helped!