How do I replace the insulated glass in an operable window?

You will need to take them to a gkassshop

If the window panes are put in with putty on the edges they can easily be replaced. Look on youtube for video instructions. If the edges are sealed with plastic edging the process is more difficult and you should consider getting a professional, although you can try finding video instructions for the type you have.

By insulated, if you mean there are two panes of glass that are separated, you will have to replace the entire window. Some of these have a vacuum between interior and exterior panes; some have argon gas. (Argon is a 'noble' gas.) It's the vacuum (good) or the gas, that gives them the insulating characteristic.

If they are double pane glass you do not need to replace the whole window as Jacky states. Just the double pane glass panel needs to be replaced. I know Ace Hardware sells double pane glass panels and they also install. A glass shop could also do it but may be more expensive. If you can remove the panels you can replace them yourself. Check a local Ace Hardware if they carry them. There should be molding on the inside that holds the panel in the frame. Use a stiff putty knife or flat screwdriver to carefully pry and remove the molding. Try not to break it.

I think this will help! https://www.todayshomeowner.com/video/how-to-replace-insulated-double-pane-glass-windows/31/

Replacing a glass unit is very easy, but usually two people are required. The process for creating an oval window is the same as for a rectangular one.

I think the easiest way is to find a specialist if you are not familiar with replacing windows, or watch 2-3 videos on YouTube before replacing.

You can request a consultation on this site https://www.unitedwindowspro.com/chicago/insulated-glass-replacement/ to understand how much it might cost