Very simple web API app - 2 methods - hard code basic authentication - asp.net-web-api

Question

I have a very simple Web API app. Just 2 methods that put (edit or insert data) - I'd like to just hard code basic authentication into the 2 methods without hugely complicating it.
What is the minimum code I need in order to require authentication the two methods - and then how do I use this code (the APIs are called from some C# code in an MVC app).
All of the examples I find online are hugely complicated - with filters or overly elaborate authentication.
My web API methods look something like this:
public IHttpActionResult Put([FromBody]ImportObject impobj)
{
// Import data here
}
And I call it like this:
public async static Task<string> Caller(ImportObject impobj)
{
string responseString = "NA";
using (var client = new HttpClient())
{
client.BaseAddress = new Uri("http://localhost");
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
// Post new object, get response
var response = await client.PutAsJsonAsync("myservice/api/meth", impobj);
// Get response content string
var resContent = response.Content.ReadAsStringAsync();
// Build user response string (just for testing)
responseString =
"<br />result: " + resContent.Result.ToString() +
"<br />status: " + resContent.Status.ToString() +
"<br />StatusCode: " + response.StatusCode + "<br />";
}
// Output response string
return responseString;
}
I just want to add basic auth to both ends - as it's so simple happy to just hard code it into both methods (this will also let me see easily how it works too).
thx.