Svet,
as was pointed in the original answer, there are two options how to customize List View via XSLT:
Below is demonstrated a complete solution how to customize List View for a Contacts list by creating a custom xsl template.
Steps:
Let's say we need to customize the view of a Contacts list
- Create a custom xsl template for a List View (see the complete code listing below)
- Save(upload) it for convenience in the same location where List form pages
reside as shown on figure below

- Open List view page in edit mode, select List View web part and go to edit web part properties, specify
XSL Link property value: ContactsView.xsl as shown on figure below
- Save web part changes
That's it.
Fig 1. Original default view for a Contacts view

Fig 2. Customized view for a contacts view after applying custom xsl template

Code listing for a custom xsl template of Contacts list view
<xsl:stylesheet xmlns:x="http://www.w3.org/2001/XMLSchema" xmlns:d="http://schemas.microsoft.com/sharepoint/dsp" version="1.0" exclude-result-prefixes="xsl msxsl ddwrt" xmlns:ddwrt="http://schemas.microsoft.com/WebParts/v2/DataView/runtime" xmlns:asp="http://schemas.microsoft.com/ASPNET/20" xmlns:__designer="http://schemas.microsoft.com/WebParts/v2/DataView/designer" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:msxsl="urn:schemas-microsoft-com:xslt" xmlns:SharePoint="Microsoft.SharePoint.WebControls" xmlns:ddwrt2="urn:frontpage:internal" xmlns:o="urn:schemas-microsoft-com:office:office">
<xsl:include href="/_layouts/xsl/main.xsl"/>
<xsl:include href="/_layouts/xsl/internal.xsl"/>
<xsl:template match="View" mode="full">
<!-- Custom Header starts here -->
<tr valign="top" class="ms-viewheadertr" style="background-color:#c0c0c0; border: ">
<th class="ms-vh-icon" scope="col" colspan="8">Contacts info</th>
</tr>
<tr valign="top" class="ms-viewheadertr" style="background-color:#c0c0c0;">
<th class="ms-vh-icon" scope="col" colspan="2"></th>
<th class="ms-vh-icon" scope="col" colspan="2">Name</th>
<th class="ms-vh-icon" scope="col" colspan="1"></th>
<th class="ms-vh-icon" scope="col" colspan="2">Phone</th>
<th class="ms-vh-icon" scope="col" colspan="1"></th>
</tr>
<tr valign="top" class="ms-viewheadertr" style="background-color:#c0c0c0;">
<th class="ms-vh-icon" scope="col" rowspan="2"><input type="checkbox" title="{$select_deselect_all}" onclick="ToggleAllItems(event,this,{$ViewCounter})" onfocus="EnsureSelectionHandlerOnFocus(event,this,{$ViewCounter})" /></th>
<xsl:call-template name="FieldRef_Attachments_header"></xsl:call-template> <!-- Render attachments header -->
<th class="ms-vh-icon" nowrap="nowrap" scope="col" onmouseover="OnChildColumn(this)">
Last Name
</th>
<th class="ms-vh-icon" nowrap="nowrap" scope="col" onmouseover="OnChildColumn(this)">
First Name
</th>
<th class="ms-vh-icon" nowrap="nowrap" scope="col" onmouseover="OnChildColumn(this)">
Company
</th>
<th class="ms-vh-icon" nowrap="nowrap" scope="col" onmouseover="OnChildColumn(this)">
Business Phone
</th>
<th class="ms-vh-icon" nowrap="nowrap" scope="col" onmouseover="OnChildColumn(this)">
Home Phone
</th>
<th class="ms-vh-icon" nowrap="nowrap" scope="col" onmouseover="OnChildColumn(this)">
E-mail Address
</th>
</tr>
<!-- Custom Header ends here -->
<xsl:apply-templates select="." mode="RenderView" /> <!-- Render default view items -->
<xsl:apply-templates mode="footer" select="." /> <!-- Render default view footer -->
</xsl:template>
</xsl:stylesheet>