How would I use my Mac air pro but connect to a iMac to use the bigger monitor
I want to use an iMac with my MacBook Air but how would I do that properly
Are you saying you want to attach an iMac to MacBook Air (There is no "Mac Air pro" model) to take advantage of the larger iMac screen? If so, a better alternative would be to buy a discrete larger monitor and attach it as an external monitor as suggested by the referring article.
Depending on exactly what you're attempting to do, and the age of your Macs, it may/may not be possible.