jQuery selector first td of each row

You should use :first-child instead of :first:

Sounds like you’re wanting to iterate through them. You can do this using .each().

Example:

$('td:first-child').each(function() {
    console.log($(this).text());
});

Result:

nonono
nonono2
nonono3

Alernatively if you’re not wanting to iterate:

$('td:first-child').css('background', '#000');

JSFiddle demo.