How To Send Enter Key To Textbox

I am working on my application that I have two forms to work with, as the one are for search and replace text and the other form are the normal form. However, I want to know how I can use the sendkeys on the form1 when I highlight for each line of the text in the textbox on form1 to press the enter key and start firing for each line of the highlighted text?And how I can do the sendkeys to the form1 when I open the search and replace dialog to input the search text in the textbox then click the button to sendkeys on my form1 and firing for each line of the highlighted text? [code]It did not send the keys on my form1 and start firing. It have just input the text as "13". I want to do the sendkeys as enter on my form1.