As HtmlAgilityPack is yet not supported in windows phone 8.1,referencing manually in the project was a trick solution. But this is not the only problem. I could use XP
If you meant to translate your current code which using XPath to be using LINQ, then this will do :
HtmlNode parent = document.DocumentNode
.Descendants("ul")
.FirstOrDefault(o => o.GetAttributeValue("class", "")
== "songs-list1")
HtmlNodeCollection x = parent.ChildNodes;
But if you expect to find methods that accept XPath in HtmlAgilityPack version for Windows Phone 8.1 universal apps or Windows RT ("I'm seeking for a block of code which will work like SelectNodes, SelectNode"), you better don't : HtmlAgilityPack & Windows 8 Metro Apps (answer by the author of HAP).