I have an XML file, I have a node and I read all ChildNodes. The name of the childNode match to a variable I have to set with the value of this childNode.
You could either do as "Default" said, or you could look into Reflection. By using the Type.GetMember(string) method you could find a member with the given name (the tag name in your XML) and set its value.
EDIT
Samich beat me, so I'll give him +1 - he's got sample code as well.