table?

Hi, how could i make a table in javascript, which would look like this:

AA CODON Number /1000 Fraction .. (this row represents the column identifiers, followed by four rows of inputs)

Ala GCG 1.00 1.86 1.00

Ala GCA 3.00 0.00 0.00

Ala GCT 2.00 2.71 1.00

Ala GCC 2.00 2.00 0.00

...

Where first two columns are fixed, and last two need mathematical calculations? I can't figure out, how to construct a table,with two fixed columns, one that reads and records in the Number column how many timeseach Codon occurred in the input (from the user). Last two need mathematical inteference which I can do, but i need a ta ble first. :S