If you want the value of [Text Box 1] on [Form 1] to copy to [Text Box 2] on
[Form 2], just write:
[Form 2]![Text Box 2] = [Form 1]![Text Box 1]
You haven't said WHEN you want this to happen. If you want it to happen when
you click a button particular button on [Form 2], then double click the
button in design view. Under the Events tab, select the row marked On Click.
Push the button on the right with the three dots (...). This will take you
into the code window. Paste the code I put above.
Note you will get an error if either form is not open at the time.
Cheers
David