diff --git a/README.md b/README.md
index b0b4489..b28068b 100644
--- a/README.md
+++ b/README.md
@@ -3,5 +3,114 @@ gnutls
 
 This is a gnutls binding for golang.
 
-This library is just work, a lot things need to be done.
+see doc [here](https://godoc.org/github.com/fangdingjun/gnutls)
 
+
+usage example
+============
+
+TLS client example
+
+	addr := "127.0.0.1:9443"
+	c, err := gnutls.Dial("tcp", addr, &gnutls.Config{
+        ServerName: "localhost",
+        InsecureSkipVerify: true,
+        })
+	if err != nil {
+		t.Fatal("gnutls dial ", err)
+	}
+	defer c.Close()
+
+	data := "hello, world"
+	if _, err = c.Write([]byte(data)); err != nil {
+		t.Fatal("gnutls write ", err)
+	}
+	buf := make([]byte, 100)
+	n, err := c.Read(buf)
+	if err != nil {
+		t.Fatal("gnutls read ", err)
+	}
+
+TLS Server example
+
+	cert, err := gnutls.LoadX509KeyPair(
+        "testdata/server/crt", "testdata/server.key")
+	if err != nil{
+		// handle error
+	}
+	l, err := gnults.Listen("tcp", "127.0.0.1:9443", &gnutls.Config{
+		Certificates: []*gnutls.Certificate{cert},
+    })
+	if err != nil {
+		// handle error
+	}
+	defer l.Close()
+	for {
+		c, err := l.Accept()
+		if err != nil {
+			log.Println("gnutls accept ", err)
+			break
+		}
+		log.Println("accept connection from ", c.RemoteAddr())
+		go func(c net.Conn) {
+			defer c.Close()
+
+			buf := make([]byte, 4096)
+			for {
+				n, err := c.Read(buf[0:])
+				if err != nil {
+					log.Println("gnutls read ", err)
+					break
+				}
+				if _, err := c.Write(buf[:n]); err != nil {
+					log.Println("gnutls write ", err)
+					break
+				}
+			}
+		}(c)
+	}
+
+AES encrypt/decrypt example
+
+	key := []byte("0123456789abcdef")
+	iv := []byte("abcdefg123456789")
+	c, err := gnutls.NewCipher(gnutls.GNUTLS_CIPHER_AES_128_CBC, key, iv)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer c.Close()
+
+	c1, err := gnutls.NewCipher(gnutls.GNUTLS_CIPHER_AES_128_CBC, key, iv)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer c1.Close()
+
+	data := []byte("1234012121212121")
+	if c == nil {
+		t.Fatal("new ciphoer failed")
+	}
+
+	// encrypt
+	dst := make([]byte, len(data))
+	err := c.Encrypt(dst, data)
+	if err != nil {
+		t.Fatal("encrypt failed", err)
+	}
+
+	// decrypt
+	data1 := make([]byte, len(data))
+	err := c1.Decrypt(data1, cdata)
+	if err != nil {
+		t.Fatal("decrypt failed", err)
+	}
+
+
+Hash example
+
+	h := gnutls.NewHash(gnutls.GNUTLS_HASH_SHA512)
+	defer h.Close()
+
+	data := []byte("1234")
+
+	h1 := h.Sum(data)