I am enlarging my basement window by cutting a larger openning on the
concrete foundation (not too large to make it unsafe structurally). My
question is: is it necessary to install a wood frame using 2X6 ? or can
I install the vinyl window directly onto the concrete opening, using
shims, foam and insulation, etc ?

What does one need a wood frame ? And what is the best way to anchor
the window to the concrete ? nail gun, concrete screw, adhesive ?

Thanks in advance for sharing your knowledge.