I have to wager its just a few screws\clips that keep it in place and is probably designed to be reversible as to what side you want the stationary panel on, and is cake to remove.

Assumingly you have the model number if you bought the replacement panel, i'd just do a quick google for the install instructions, and they probably tell you what exactly you need to do.

Edit: Anderson is pretty good about having full manuals online https://www.andersenwindows.com/for-professionals/documents/