求翻译：第一，上车后将身体对正方向盘并保持正直，后背轻靠于后背椅上，然后根据身高对座位调整至合适状态，系好安全带；是什么意思？

First, after boarding on the steering wheel and keep the body upright, back light on was back on the Chair, then according to height to adjust the seat to the appropriate State, seatbelts;