There is a blue bed , a black case ,a black chair  and black walls in my bedroom .或者是There is a blue bed in my bedroom, black box, black cabinets, black chair, white wall。或者是My bedroom has blue beds, black boxes, black cabinets, black chairs, white walls，三種方式都是這個意思的，你可以參考一下的，選擇比較合適的，或者是你喜歡的都行。