Trying to combine data tables into one to do multiple plots on the same graph.

I have two tables, and a plot associated with each. I want to plot the data in the tables on the same graph.

Therefore I am trying to combine in the tables to plot the data on the same graph. But it's like the tables are in read only mode, so I can't import any data to them, unless by creating a new table, but then I will get a new graph.