Accessing other programs

[gorcq]

I am trying to write a program that will automatically enter text into a textbox and then click on a button. The problem is that both the textbox and the button are on a separate form in an unrelated program, which will be running at the same time as my program. I do not have access to the second program's code, so I cannot integrate it into my project or solution.

Is there any way I can do this?

Thank you, Robby

Edit: The second program is made so that pressing the Enter key while focused on the textbox is equivalent to clicking on the button. I don't know whether or not this is useful information.