C Sharp :: How To Convert Textbox Value To String Value

i create two forms add a password in first form throgh user input and second form will open i want that password will automatically be added to second form. first form is ok working according to my expactations but problem that it does not enter pssword in second form i reference that textbox that is

stdfrm std=new std();
std.a=txtpwd;

it displays an error that cannot implicitly convert type system.windows.forms.textbox to string