fitting pvc window to steel shed

Hello There,
currently building a steel workshop in the back garden. I am building it with 40mm box iron and box profile sheeting.
My problem is that i want to put in a couple of pvc windows i picked up. how would i go about fitting them into the sides of the shed? i am not sure how to make the window fit in with the profile of the sheeting if you know what i mean.
any help greatly appreciated, i have searched the net for days and found nothing!
Thanks in advance

You should be able to strap them to the steel frame using galvo-band or the proprietary straps that come with the windows.
To weather proof I would expanding foam fill the surrounds, mastic the joints and then use angle beads to match the profile sheeting to create a reveal surrounding the windows. You would use DPC to the head of the window ensuring that the sheeting laps over the DPC which laps over the window head.
The detail would be similar to that used in fitting windows to timber frame structures. If you email me directly I can send a drawing which may be of help. You would need to adjust to suit your particular use, but it will point you in the right direction.

Take a walk in your local industrial estate, you will see the cill, side and head details. Ask the supplier of your sheeting to bend the flashings for you.

good idea, thanks