LINQ to XML query from querystring

I need to create xml files based on querystring values.

My xml file:

<Products><Product><Name>Name</Name><Category>Books</Category><SubCategory>Drama</SubCategory></Product><Product><Name>Name</Name><Category>Books</Category><SubCategory>Action</SubCategory></Product><Product><Name>Name</Name><Category>Paper</Category><SubCategory></SubCategory></Product>

So if i type ?filter=Books,Paper i need to select Product where Categorycontains value from querystring.

Then if i type ?filter=Books,Paper&filter2=Drama i still need Product where Category contains filter1 but if Product element containsSubCategory that containsfilter2 i need to select just those.

So with: ?filter=Books,Paper&filter2=Drama i need to get xml that looks like this:

<Products><Product><Name>Name</Name><Category>Books</Category><SubCategory>Drama</SubCategory></Product><Product><Name>Name</Name><Category>Paper</Category><SubCategory></SubCategory></Product></Products>

Also some products may have empty SubCategory element. I don't know if that is important.

My query looks like this:

var items = from el in SimpleStreamAxis(esysPath, "Product")                        where filter.Contains(el.Element("Category").Value.Trim())                        where filter1.Contains(el.Element("SubCategory").Value.Trim())                        select new                        {                            ProductID = el.Element("ID").Value,                            Name = el.Element("Name").Value,                            Price = el.Element("Price").Value,                            Picture = el.Element("Picture").Value                        };

This is selecting all Product elements where filter1 contains SubCategory.

So can anyone point me in to right direction on how to write this query.

Thanks.