I for one have never introduced myself in the newbie section. It is not a prerequisite for posting a car for sale ad. There are many people that haven't either.
If someone were to buy a car posted on the internet without doing some investigating first, before sending money, they'll probably lose that money. I did an ebay purchase of my Vert, before any thing was done, I made damn sure that there was a car and legit seller.
As for saying a car is "SOLID" Solid means different things to different people. To me solid means it has thick strong frame rails, torsion bar crossmember, and rocker panels. Solid to others may mean that it doesn't need ANY rust repair bigger that a 1" square.
Good luck with your sale Newbie!