POST data from https://apiadv.sintia.com.ar/Help/Api/POST-Ratificacion-Login

func Login(username, password string) {
    url := "https://apiadv.sintia.com.ar/Ratificacion/Login"
    var jsonStr = []byte(`{"Username":"` + username + `","Password":"` + password + `"}`)
    req, err := http.NewRequest("POST", url, bytes.NewBuffer(jsonStr))
    req.Header.Set("Content-Type", "application/json")

    client := &http.Client{}
    resp, err := client.Do(req)
    if err != nil {
        panic(err)
    }
    defer resp.Body.Close()
    fmt.Println("response Status:", resp.Status)
    fmt.Println("response Headers:", resp.Header)
    body, _ := ioutil.ReadAll(resp.Body)
    fmt.Println("response Body:", string(body))
}