I would like to change the first Cell and the last Cell of a Range using
VBA

I have this code;

Dim MyRange As Range
Set MyRange = Selection

lets say the selection was ($A$1:$H$3), so I now have a MyRange of $A$1:$H
$3 and using;

MsgBox "My Range is " & MyRange.Address

I get a message that says that this is true.

Now I want to change the first Cell ($A$1) or the last Cell ($H$3) to
something different so I have tried these variations;

MyRange = Range(MyRange(1, 1).Address, H13) - Also tried using 'Set'
Set MyRange = Range("H3", "K8")

but using the message after either of these lines shows that the original
range limit is still applying.

Can anyone tell me how to set the first or last cell properties using VBA ?

Any help appreciated

Thanks