HttpClient httpClient = new HttpClient();
var jsonReponse = await httpClient.GetStringAsync("http://localhost:xxxxx/api/LogIns");
logInResult = JsonConvert.DeserializeObject<List<LogIn>>(jsonReponse);

var logIn = new Models.LogIn()
{
    Username = "username",
    Password = "password"
};
var logInJson = JsonConvert.SerializeObject(logIn);

HttpClient httpClient = new HttpClient();
var httpContent = new StringContent(logInJson);
httpContent.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/json");

await httpClient.PostAsync("http://localhost:56267/api/LogIns", httpContent);