How to create an overview in Numbers of my External drives

I suspect there's more to what you're asking, but cell references are pretty straightforward... for any given cell, to reference another cell on the same table, just use it's coordinates.

e.g. Cell A1:

=B2

this references the cell B2 on the same table.

If you want to reference a cell on a different table on the same sheet, preface it with the table name:

=Data Table::B2

this will reference cell B2 in the table labelled 'Data Table'.

One cool thing is that if there is only one 'Data Table' on all the sheets in the document, Numbers will find it.

If you haven't named your tables, you likely have multiple 'Table 1', 'Table 2', etc., so in this case, to get the one you want you can preface it with the sheet name:

=Sheet 2::Table 3::B4

will get cell B4 on Table 3 on Sheet 2 (you can substitute actual sheet and/or table names if you've labelled them.

In addition, rather than typing it all out, select the cell on your main table and type '=', then you can change to the sheet you want and click the cell you want to reference, and Numbers will fill in the details.

Then I guess I don’t understand what it is you’re trying to do.

can you explain in more detail?

what is in your ‘data’ sheets (presumably your file listings?), and what are you trying to build that references it?