Text break into two part

[C# Programming]

hi,
i am beginner in c#, i need tour help, i want two break textbox text in two part
For example
textbox1.text = "ABT-001"
ABT-001 break into "ABT-00" and "1"
textbox2.text = "ABT-00" and textbox3.text="1"

Hope you understand by question

Thanks