visual programming please help as soon as possible

Lab Exercise: Write a C#.Net program that searches the text input box for specific word entered in boxe and replaces this text with one entered in box3. Also print the text after replacement in the richTextBox, separating each letter on a line, and write the content of the richTextBox in a text file called result.txt Sample input: This Java Lab is the best. Old string: Java New string: Csharp Result string: This Csharp Lab is the best. Before Formi Input: This Java Lab is the best Old: New: After Input box pirmi Input: This Java Lab is the best Old: Java New: Chap Result: This Csharp Lab is the best Result: Click here BOX3 Click here Box 2