If you just want the form to fill the entire Access window, you can do this:
Open the form in design view.
Display the form's Property Sheet.
Scroll down to the entry for OnOpen.
Highlight that entry, and click the down arrow at the right of the box.
Select [Event Procedure].
Now click on the button with 3 dots at the end of that line.
A code window will open, with the cursor between these two lines:
Private Sub Form_Open(Cancel as Integer)
End Sub
Between those two lines, type this:
DoCmd.Maximize
You should now be able to close that (code) window, and save your form.
Now when you open it, it will fill the entire Access Window.
If you are thinking of either making the Access Window fill the entire
screen, or displaying your form without the Access window, be aware that
while these things can be done by advanced programmers, they do not
constitute "baby steps".
HTH
- Turtle