String Bytes - How To Send / Read And Parse

I am using sockets and such for a while now, and want to go an step further in this. Now for example lets say an client would send [lenghtofstringinbytes]string[somethingelseinbytes]another thing.
How can I send/read/parse it?

Now I am doing this:
Private Sub onDataArrival(ByVal ar As IAsyncResult)
Try
Dim obj_SocketState As StateObject = CType(ar.AsyncState, StateObject)
Dim obj_Socket As Socket = obj_SocketState.WorkSocket
Dim sck_Data As String
[Code] .....

So using Getstring for it, but thats not the way for this as you get nothing else but an empty string back. So I have to parse it without converting it to an string.