Get all atributes of an XML to an 2d or 3d string array in C#

For my project I'm trying to translate or decrypt a XML API answer to an usable array of all the information.

Here is an example of the XML I'm receiving:

<users>
<User LoginName="test1" Owner="" Alias="" UserType="PAID" ClientType="OBM" Quota="10737418240" Timezone="GMT+08:00 (CST)" Language="en" DataFile="1" DataSize="1536" RetainFile="0" RetainSize="0" EnableMSSQL="Y" EnableMSExchange="Y" EnableOracle="Y" EnableLotusNotes="Y" EnableLotusDomino="Y" EnableMySQL="Y" EnableInFileDelta="Y" EnableShadowCopy="Y" EnableExchangeMailbox="N" ExchangeMailboxQuota="0" EnableNASClient="Y" EnableDeltaMerge="Y" EnableMsVm="N" MsVmQuota="0" EnableVMware="N" VMwareQuota="0" Bandwidth="0" Notes="" Status="ENABLE" RegistrationDate="1302687743242" SuspendPaidUser="N" SuspendPaidUserDate="20140503" LastBackupDate="1302699594652" EnableCDP="Y" EnableShadowProtectBareMetal="Y"EnableWinServer2008BareMetal="Y"
Hostname="123.abc.com" FileSizeLimit="52428800" ExcludeNetworkShare="Y"
><Contact Name=""Email="www@qqq.com"/>
</user>

I've succeeded to get one Attribute at once by using this code below:

/// <summary>
        /// Get attribute from XML file USE ONLY AS DEMO
        /// </summary>
        /// <param name="inputXML">XML string</param>
        /// <param name="requestVar">The requested variable in the XML response</param>
        /// <param name="parameter">Where the requested variable is located</param>
        /// <returns>string of all requested variables</returns>
        public static String GetAttribute(string inputXML, string requestVar, string parameter)
        {
            string vars = "";
            XmlDocument xml = new XmlDocument();
            xml.LoadXml(inputXML);

            XmlNodeList xnList = xml.GetElementsByTagName(parameter);
            foreach (XmlNode xn in xnList)
            {
                vars = vars + xn.Attributes[requestVar].Value;
            }
            return vars;
        }

This function needs the node names where it can be found. For this project are many API calls necessary and would like a function which puts all the attributes in a string array. So far I tried to translate this part:

vars = vars + xn.Attributes[requestVar].Value;

to this:

foreach (XmlAttribute xa in xn)
{
    vars[i, j, k] = xa.Value;
    k++;
}

and I Also tried:

for (k = 0; k < xn.Attributes.Count; k++ )
{
    vars[i, j, k] = xn.Attributes[k].Value;
}

But both codes won't work. How do I get a simpel for loop or foreach, which gets all the attributes in the array? And can this also be done with:

XmlNodeList xnList = xml.GetElementsByTagName(parameter);

The i, j and k vars are used in the multiple loops: i is used for XmlNodeList, the j is used for the XmlNode and the k is used for the XmlAttribute.

In this array I would like to get all the info of the XML file in the same order, only the parts between the '""' is needed.

vars[0][0][0]= would stand for: <Users><User LoginName= (vars[<Users>][<User][LoginName]=

This is the function as far as I'm now:

public static String[,,] GetVars(string inputXML)
        {
            string[,,] vars = new string[100,50,50];
            int i, j, k;
            XmlDocument xml = new XmlDocument();
            xml.LoadXml(inputXML);

            i = j = k = 0;
            XmlNodeList xnList = xml.GetElementsByTagName("Users");
            foreach (XmlNode xn in xnList)
                {
                    foreach (XmlAttribute xa in xn)
                    {
                        vars[i, j, k] = xa.Value;
                        k++;
                    }
                    k = 0;
                    j++;
                }
                j = 0;
            return vars;