OK. Today's dumb question.

As a slightly illiterate internet user I can't work out how to guarantee a "Y" fare through UAL.com.

I've booked a couple of flights for the next few weeks (SFO to PDX) and although the fare code stated "Y" in the flight selection, after I selected the flights and booked them the receipt when printed showed "Q".

This I presume means no upgrade for me.

What did I do wrong ?.