At SL we can find chairs which have Letters on it. The magic
happens when appears the first letter of your avatar name because as soon as
you sit you can earn Lindens. For example, my name is Panchui, so I will be
looking for the letter P.
If you renamed your Avi the letter you are looking for is the initial letter from your original name, which is the one you choose when you created your account at SL.
All you have to do is follow the rules of the sim where the chair is located. Some places may want you to join their group and activate it every time you wish to use the chair.
Once you know the local rules from the owner of the chair
you have to be there before the letter you look for is announced. Even you see it
there, if you weren’t attending the place yet by the time it was announced in
local chat you will miss the chance of earning lindens.