to find where she was enslaved, you need to trace her backwards through census records. This isn't always easy, especially if the person moved out of the area they lived in prior to 1870 and if they have a common name. But if they stayed in the same area, you should be able to find them. I see you have an 1880 census. Is she in the same place in 1870? if so, find out which slave owners lived in that area in 1860. Then you would need to find records for each slave owner such as bills of sales, wills, lists of slaves, etc. to see if one of them lists her. All this is not easy and can take a lot of time.