Add text or link frame
Selecting New frame > Text frame or New frame > Link frame from the frame information menu leads to the same dialogue (shown below).

The title bar will show whether a text or link frame is being added. The only difference will be in the list of frames presented via the popup menu button to the right of the frame ID. A shortened menu is shown below for adding a text frame to a v. 2.3 tag. The list of allowed frames will be a little different for adding to a v. 2.4 tag. The list of link frames offered will be the same for both versions of tag. Clicking on a popup menu item will copy that frame type in to the frame ID field for adding.

The text content for the frame is entered in to the main content field.
A small number of textual frames allow (or require) a descriptor field as well as the main content. For example COMM or TXXX. In this case the add frame window will be modified to include the two separate fields for descriptor and content.

Some of these text frames that can be added have differing specifications. Some must consist only of numerals of predefined length (eg TDAT is a numeric string DDMM always four characters long). Many text frames are single alphanumeric string, but some allow LF to split the content in to paragraphs (eg COMM). ID3TagEd does some rudimentary checking, but it is wise to check the ID3 specification when adding such frames. Remember, other software that makes use of the frames you have added will probably assume the frames conform to the specification when decoding them.
Once satisfied with the content, clicking the Add frame button will construct the frame, and add it to the list of frames in the tag. It is still necessary to Write the tag before the change is made permanent in the mp3 file.