Update README

README.md

@@ -34,7 +34,7 @@ Version specific details can be accessed through the subpackages.
         "github.com/mikkyang/id3-go/v2"
     )
 
-# Opening a File
+# Quick Start
 
 To access the tag of a file, first open the file using the package's `Open`
 function.
@@ -45,7 +45,7 @@ It's also a good idea to ensure that the file is closed using `defer`.
 
     defer mp3File.Close()
 
-# Accessing Information
+## Accessing Information
 
 Some commonly used data have methods in the tag for easier access. These
 methods are for `Title`, `Artist`, `Album`, `Year`, `Genre`, and `Comments`.
@@ -53,7 +53,7 @@ methods are for `Title`, `Artist`, `Album`, `Year`, `Genre`, and `Comments`.
     mp3File.SetArtist("Okasian")
     fmt.Println(mp3File.Artist())
 
-## ID3v2 Frames
+# ID3v2 Frames
 
 v2 Frames can be accessed directly by using the `Frame` or `Frames` method
 of the file, which return the first frame or a slice of frames as `Framer`
@@ -68,3 +68,16 @@ The example provided does not check for errors, but it is recommended to do
 so.
 
     lyricsFrame := mp3File.Frame("USLT").(*v2.UnsynchTextFrame)
+
+## Adding Frames
+
+For common fields, a frame will automatically be created with the `Set` method.
+For other frames or more fine-grained control, frames can be created with the
+corresponding constructor, usually prefixed by `New`. These constructors require
+the first argument to be a FrameType struct, which are global variables named by
+version.
+
+    ft := V23FrameTypeMap["TIT2"]
+    text := "Hello"
+    textFrame := NewTextFrame(ft, text)
+    mp3File.AddFrames(textFrame)