Entity Framework Core

Hi,
    how do I create an Edit for the below.
The code pasted works, there is no error.
My question is about CRUD. I would like functionality for (CRUD - Update) / "EDIT" on the Blog.

I think it would be
1. Get row by Id
2. Edit
3. Refresh view

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using ExploreCalifornia.Models;
using Microsoft.AspNetCore.Authorization;
namespace ExploreCalifornia.Controllers
{
    [Route("blog")]
    public class BlogController : Controller
    {
        private readonly BlogDataContext _db;
        public BlogController(BlogDataContext db)
        {
            _db = db;
        }
        [Route("")]
        public IActionResult Index(int page = 0)
        {
            var pageSize = 2;
            var totalPosts = _db.Posts.Count();
            var totalPages = totalPosts / pageSize;
            var previousPage = page - 1;
            var nextPage = page + 1;
            ViewBag.PreviousPage = previousPage;
            ViewBag.HasPreviousPage = previousPage >= 0;
            ViewBag.NextPage = nextPage;
            ViewBag.HasNextPage = nextPage < totalPages;
            var posts =
                _db.Posts
                    .OrderByDescending(x => x.Posted)
                    .Skip(pageSize * page)
                    .Take(pageSize)
                    .ToArray();
            if (Request.Headers["X-Requested-With"] == "XMLHttpRequest")
                return PartialView(posts);
            return View(posts);
        }
        [Route("{year:min(2000)}/{month:range(1,12)}/{key}")]
        public IActionResult Post(int year, int month, string key)
        {
            var post = _db.Posts.FirstOrDefault(x => x.Key == key);
            return View(post);
        }
        [Authorize]
        [HttpGet, Route("create")]
        public IActionResult Create()
        {
            return View();
        }
        [Authorize]
        [HttpPost, Route("create")]
        public IActionResult Create(Post post)
        {
            if (!ModelState.IsValid)
                return View();
            post.Author = User.Identity.Name;
            post.Posted = DateTime.Now;
            _db.Posts.Add(post);
            _db.SaveChanges();
            return RedirectToAction("Post", "Blog", new
            {
                year = post.Posted.Year,
                month = post.Posted.Month,
                key = post.Key
            });
        }
    }
}
Thanks,