how does one do cell references in Numbers

=Table 2::B1

=Sheet 2::Table 1::B1

Created the same as described before: type it in or click on the cell. If the cell is in a table on the same sheet, just scroll to the other table and click on the cell. If it is on another sheet, click on the sheet name then scroll to the table and click on the cell.

... and for reference to a cell in a different table of the same document?

Answering your second question, if "in a different spreadsheet" means "in a different file/document", then the answer is no. You can reference cells in any table of the same document but not a cell in another document.

Your first question sounds like a "spreadsheets 101" question. You might want to read the help file in the menu Numbers/Help/Numbers Help. A basic answer to your question is:

Select a cell. Type an = sign then type B1 and you will end up with the formula =B1 which references cell B1

or

Select a cell. Type an = sign then click on cell B1 and you will end up with the formula =B1 which references cell B1

Expand from that idea to make more complex formulas.

you can't create references between sheets if you're using Numbers for iCloud Beta. It only works in Numbers for Mac.

On my machine you can definitely create references between sheets in Numbers for iCloud beta. It's just that you have to type in the reference; you cannot just click on a reference in a different sheet the way you can in Numbers for Mac or tap the way you can in Numbers for iOS. But Numbers for iCloud does support references between sheets.

SG

As SGIII said, you have to type in references to other sheets when using iCloud beta. And if there are spaces (or maybe other unusual characters) in your sheet or table name you have to enclose the name with half-quotes:

='Sheet 1'::'Table 1'::B1

Just for information, you can't create references between sheets if you're using Numbers for iCloud Beta. It only works in Numbers for Mac.