Selenium XPath locators examples:

1.

div id="submenu_electronics" class="submenu" data-submenu-key="electronics">
    <div class="line shopby allow-overflow">
    <div class="line main-section" data-tracking-id="nmenu_sub_electronics">
        <div id="menu-electronics-tab-0-content" class="tab-content " data-tracking-id="Categories">
            <ul class="unit size1of5 menu-column even ">
                <li class="heading">


Xpath in firebug console:
$x("//div[@id='submenu_electronics' and @class='submenu']/div[2]/div/ul[1]")
or
$x("//div[@id='submenu_electronics' and @class='submenu']//../ul[1]")

@col_linesheet_ref = Element.new(:xpath,
                                 "//table[contains(@id,'channelSubTable')]/thead/tr/th[1]")
@col_linesheet_name = Element.new(:xpath,
                                  "//table[contains(@id,'channelSubTable')]/thead/tr/th[2]")
@col_linesheet_season = Element.new(:xpath,
                                  "//table[contains(@id,'channelSubTable')]/thead/tr/th[3]")
@col_mapping_errs = Element.new(:xpath,
                                    "//table[contains(@id,'channelSubTable')]/thead/tr/th[4]")
@col_new_lines = Element.new(:xpath,
                                "//table[contains(@id,'channelSubTable')]/thead/tr/th[5]")

@link_channel = Link.new(:xpath,"//a[@data-test='menuHeaderChannels']")
@eleh1 = Element.new(:xpath, "//div[@id='page-heading']")
@combo_retailer = ComboBox.new(:xpath, "//select[@id='retailerId']")

@tbl_channels = Element.new(:xpath, "//table[@id='channels-list']")

@tbl_subtable=Element.new(:xpath, "//table//table")
@tbl_subtbl_lines_ref = Element.new(:xpath, "//table//table/tbody/tr/td[1]")
@table_channels = Element.new(:xpath, "//table/tbody/tr/td[2]")

@ele_overview = Element.new(:xpath, "//h4[contains(text(), 'Overview')]")