Been there, done that got a closet full of Airstream T-shirts.
That was 5 years ago.
As for the website, you found it. Good place to start... do a search for "newbie" threads. Decide on new, gently pre-enjoyed and vintage (true money pit but classy!).
Take your time searching, thinking about and selecting a trailer to avoid the serial of buying two and getting a handle of "Foiled Again"....
Start trimming down NOW if you're really planning to downsize from a house to an Airstream.
If you've never lived in an RV, renting one for a week is "expensive" but far far far less expensive than buying a $50K unit that turns into a piece of lawn art growing growing moss because you never use it. Many KOA's actually have an Airstream rental unit (most are not available until spring, but check Savannah and further south... might as well get a little Vay-Kay while experimenting, No?
Find a rally and attend - most folks love to show off their Airstreams - especially if you are considerate and remove your shoes (clogs) at the door. There are a lot of sizes, configurations, etc. to choose among. Make careful notes.
Prepare to pounce. Once you know what you're looking for, if it comes up, you many have only hours to buy it before someone else with a wad of cash beats you to it. (If buying used/vintage.) New, you can special order another one.
Most of all we're dead serious about having fun (yes I stole that OL-62).
Enjoy the process as much as the purchase.