Lexical Editor: How to replace selected line of text

Question

I am looking to replace a selected text with multiple lines, but I am unable to find the exact solution in the documentation or stackoverflow.

Here is my code:

editor.update(() => {
    const paragraphNode = $createParagraphNode();
    const newNode = $createTextNode(popoverContent);
    paragraphNode.append(newNode);

    // How can I replace the selected nodes/text with paragraphNode? \*/
});

This is the input from Editor, first line of a is not selected

ab
cde 
fghi 
jklmn

I want to exclude the letter "a" from the replacement process. Could someone please provide guidance on how to achieve this?