How to add Jwt token authentication in Web API

I have created web api project by selecting an empty project in vs.

I want to use jwt token-based authentication, I have installed nugate package IdentityModel.Tokens.Jwt.

I have added Authentication filter (created a custom class AuthenticatAtribue and implement iAuthenticationFilter)

please provide code for below methods

public async Task AuthenticateAsync(HttpAuthenticationContext context, CancellationToken cancellationToken)
{
// 1. Look for credentials in the request.
HttpRequestMessage request = context.Request;
AuthenticationHeaderValue authorization = request.Headers.Authorization;
// 2. If there are no credentials, do nothing.
if (authorization == null)
{
return;
}
// 3. If there are credentials but the filter does not recognize the
// authentication scheme, do nothing.
if (authorization.Scheme != "Basic") // is basic ok here i want token based authentication
{
return;
}
// 4. If there are credentials that the filter understands, try to validate them.
// 5. If the credentials are bad, set the error result.
if (String.IsNullOrEmpty(authorization.Parameter))
{
context.ErrorResult = "what should write here"
return;
}
Tuple<string, string> userNameAndPassword = null;// ExtractUserNameAndPassword(authorization.Parameter);
if (userNameAndPassword == null)
{
//context.ErrorResult = new AuthenticationFailureResult("Invalid credentials", request);
context.ActionContext.Response = new HttpResponseMessage(HttpStatusCode.Unauthorized);
}
// string userName = userNameAndPassword.Item1;
// string password = userNameAndPassword.Item2;
var identity = new GenericIdentity(); what should i write here
IPrincipal principal= new GenericPrincipal(identity, null);//// await AuthenticateAsync(userName, password, cancellationToken);
if (principal == null)
{
context.ErrorResult = null;// new AuthenticationFailureResult("Invalid username or password", request);
}
// 6. If the credentials are valid, set principal.
else
{
context.Principal = principal;
}
}
public Task ChallengeAsync(HttpAuthenticationChallengeContext context, CancellationToken cancellationToken)
{

please provide code for this section