How to find a line starts with "ABC" in a word document without using interop dll in c#

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C#

I have to open a word document using docX dll and insert some images below the heading IMAGES: on the word document.
could anyone please help me to find the line starts with Images in the word document using DocX dll in c#,
i can insert the image by using the below code but am not able to find the exact place to fix those images.
// Add an Image to the docx file

Novacode.Image img = doc.AddImage(@"C:abc.jpg");
Picture pic = img.CreatePicture();
pic.Width = 600;
pic.Height = 300;

I have gothrough this linkC#: Create and Manipulate Word Documents Programmatically Using DocX[^]

Note: I am not using interop dll to open or save the word documents.

Thanks in Advance