ASP.NET Can not Resolve System.Net, System.Http

Question

I apologize for this question, but I am absolutely new to .NET development (coming from Java...) I am trying to test this example of API:

https://learn.microsoft.com/en-us/aspnet/web-api/overview/getting-started-with-aspnet-web-api/tutorial-your-first-web-api

My code complains on "Cannot Resolve": using System.Net; using System.Web.Http; ApiController IHttpActionResult

Code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Web.Http;
using WebApiSandobox01.Models;

namespace WebApiSandobox01.Controllers
{
    public class ProductsController:ApiController
    {
        Product[] products = new Product[] 
        { 
            new Product { Id = 1, Name = "Tomato Soup", Category = "Groceries", Price = 1 }, 
            new Product { Id = 2, Name = "Yo-yo", Category = "Toys", Price = 3.75M }, 
            new Product { Id = 3, Name = "Hammer", Category = "Hardware", Price = 16.99M } 
        };`enter code here`

        public IEnumerable<Product> GetAllProducts()
        {
            return products;
        }

        public IHttpActionResult GetProduct(int id)
        {
            var product = products.FirstOrDefault((p) => p.Id == id);
            if (product == null)
            {
                return NotFound();
            }
            return Ok(product);
        }
    }
}

I have Rider 2022.1 as IDE I went through this question (unfortunately Nuget is little bit different in 2022, ...):

System.Net, cannot resolve symbol 'Net'

Going to Project -> properties, Target Framework is: .NETFramework v.4.8

I have .NETFramework v.4.8 Developer Pack installed in:

C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.8

I can see files:

System.Net.dll System.Net.Http.dll System.Net.Http.WebRequest.dll

Under Settings -> Toolset & Build I tried various MS Build versions (4.0, 17.0) - No difference

Can you advice me, how to resolve this? I am relly new to .NET and Rider. I have spent almost one day on this already....

Let me specify, what I want to achieve in this way, also reacting on your questions:

Currently I am trying to create "sandbox", anything, which will resemble technologies above, eg:

• due to my experiences with IntelliJ, I have chosen Rider
• using CLR (I would like my code to be "indpendent" as Java)
• use IIS (as Tomcat in Java world)
• therefore I do not want to create .exe ( I was able to create, using template ASP.NET Core Web API the service, but it is .exe file)
• when I use dotnet new --list, there is no other template for API other than ASP.NET Core Web API)

Bellow mentioned link again has Program.cs file....:

https://learn.microsoft.com/en-us/aspnet/core/tutorials/first-web-api?view=aspnetcore-6.0&tabs=visual-studio-code

Yes, I found that Rider has "AddReference", but it does not allow to add "System.Web.Http" to resolve [ApiController] reference

Do you know about some simple example code, which can create RestService, running on top of IIS, using CLR with Net6.0?