How do I open any file in C#

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C#

file

treeview

I making a file browser which I want to load files into the code editor, a bit like the solution explorer in visual studio. I have this piece of code which opens a folder browser dialog and makes a file browser like this one. I want it so that if you double-click a file it will open that file in the editor. I am using a tree view and an image list.

private void openFolderToolStripButton_Click(object sender, EventArgs e)
        {
            FolderBrowserDialog obd = new FolderBrowserDialog();
            if (obd.ShowDialog() == DialogResult.OK)
            {
                path = obd.SelectedPath;
                Console.WriteLine("path is found");
                Console.WriteLine(path.ToString());
                if (path != "")
                {
                    flowLayoutPanel1.Width = 200;
                    DirectoryInfo directoryInfo = new DirectoryInfo(path);
                    DirectoryInfo[] directories = directoryInfo.GetDirectories();
                    foreach (FileInfo file in directoryInfo.GetFiles())
                    {
                        
                        if (file.Exists)
                        {
                            TreeNode nodes = treeView1.Nodes[0].Nodes.Add(file.Name);
                            SetImageExtension(file.Name, nodes);
                        }
                    }

                    if (directories.Length > 0)
                    {
                        foreach (DirectoryInfo directory in directories)
                        {
                            TreeNode node = treeView1.Nodes[0].Nodes.Add(directory.Name);
                            node.ImageIndex = node.SelectedImageIndex = 0;
                            foreach (FileInfo file in directory.GetFiles())
                            {
                                if (file.Exists)
                                {
                                    TreeNode nodes = treeView1.Nodes[0].Nodes[node.Index].Nodes.Add(file.Name);
                                    SetImageExtension(file.Name, nodes);
                                }
                            }
                        }
                    }
                }
            }
        }

What I have tried:

Well, I have this for and not sure how to actually read from the file.

private void TreeView_NodeDoubleClick(object sender, MouseEventArgs e)
        {
            string nodeText = treeView1.SelectedNode.Text;
            string nPath = path + @"\" + nodeText;
            using (var fileStream = new FileStream(nPath, FileMode.Open, FileAccess.Read))
            {
                Console.WriteLine(nPath);
            }
        }