wo3men wan3shang qi1 dian3 jian4mian ba.
*the numbers represent the tone marks for the pinyin.
*It should be "晚上" , meaning "evening/night" not "下午"(afternoon). Note that 晚上(the time period) comes before the actual time.
*吧 here shows a suggestion and it's optional but I suggest you add it, as it sounds more friendlier as opposed to an order.