Go Client Connect to an URL with Socket

I'm newbie in Go. I have a server run FastAPI Python. I have already run websocket request in 127.0.0.1:8000/register.

@app.websocket("/register")
async def websocket_endpoint(websocket: WebSocket):
    await websocket.accept()
    while True:
        data = await websocket.receive_text()
        await websocket.send_text(f"Message text was: {data}")

I want to create an app work as a client by Go. This app use socket connect to this URL and send info to create account. But when I try to use example code in google:

package main

import "net"
import "fmt"
import "bufio"
import "os"
import "log"

func main() {
  // connect to server
  conn, err := net.Dial("tcp", "127.0.0.1:8000/register")
  if err != nil {
    log.Println(err)
}
  for { 
    // what to send?
    reader := bufio.NewReader(os.Stdin)
    fmt.Print("Text to send: ")
    text, err := reader.ReadString('\n')
    if err != nil {
        log.Println(err)
    }
    // send to server
    fmt.Fprintf(conn, text + "\n")
    // wait for reply
    message, err := bufio.NewReader(conn).ReadString('\n')
    if err != nil {
        log.Println(err)
    }
    fmt.Print("Message from server: "+message)
  }
}

It's not working because of dial tcp: lookup tcp/8000/register: getaddrinfow: The specified class was not found

As I understand that it cannot lookup for this link, it only lookups when it's a IP Address.
How can I create a Socket request to an URL?

use github.com/gorilla/websocket
example:

package main

import (
	"flag"
	"log"
	"net/url"
	"os"
	"os/signal"
	"time"

	"github.com/gorilla/websocket"
)

var addr = flag.String("addr", "127.0.0.1:8080", "http service address")

func main() {
	flag.Parse()
	log.SetFlags(0)

	interrupt := make(chan os.Signal, 1)
	signal.Notify(interrupt, os.Interrupt)

	u := url.URL{Scheme: "ws", Host: *addr, Path: "/register"}
	log.Printf("connecting to %s", u.String())

	c, _, err := websocket.DefaultDialer.Dial(u.String(), nil)
	if err != nil {
		log.Fatal("dial:", err)
	}
	defer c.Close()

	done := make(chan struct{})

	go func() {
		defer close(done)
		for {
			_, message, err := c.ReadMessage()
			if err != nil {
				log.Println("read:", err)
				return
			}
			log.Printf("recv: %s", message)
		}
	}()

	ticker := time.NewTicker(time.Second)
	defer ticker.Stop()

	for {
		select {
		case <-done:
			return
		case t := <-ticker.C:
			err := c.WriteMessage(websocket.TextMessage, []byte(t.String()))
			if err != nil {
				log.Println("write:", err)
				return
			}
		case <-interrupt:
			log.Println("interrupt")

			// Cleanly close the connection by sending a close message and then
			// waiting (with timeout) for the server to close the connection.
			err := c.WriteMessage(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseNormalClosure, ""))
			if err != nil {
				log.Println("write close:", err)
				return
			}
			select {
			case <-done:
			case <-time.After(time.Second):
			}
			return
		}
	}
}

or nhooyr.io/websocket - is a minimal and idiomatic WebSocket library for Go
https://github.com/nhooyr/websocket

ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
defer cancel()

c, _, err := websocket.Dial(ctx, "ws://localhost:8080/register", nil)
if err != nil {
	// ...
}
defer c.Close(websocket.StatusInternalError, "the sky is falling")