$.fn.grid = function () {

    var that = $(this);

    var addHeader = function addHeader(arr) {
        var tr = $('<tr>');
        arr.forEach(function (item) {
            var th = $('<th>').text(item);
            th.appendTo(tr);
        });

        tr.appendTo(that);
    };

    var addRow = function addRow(arr) {
        var tr = $('<tr>');
        arr.forEach(function (item) {
            var td = $('<td>').text(item);
            td.appendTo(tr);
        });

        tr.appendTo(that);
    };

    return {
        addHeader: addHeader,
        addRow: addRow
    }
};

var grid = $('#myGrid').grid();

grid.addHeader(['First Name', 'Last Name', 'Age']);
grid.addRow(['Bay', 'Ivan', 50]);
grid.addRow(['Kaka', 'Penka', 26]);