Owning and selling land is an exclusive privilege in Second Life. For instance a land owner can manage access to the land, change its shape, divide it in smaller pieces or sell it. Residents can use various tools and menus to do so. Here is a selection and short description.
"Land Tool" is the most popular tool in Second Life. It can be opended by right-clicking on a piece of land. The menu opens and for basic options will be available.
The "General Tab" displays all general information about the land. Like name of the land and owner. Also here is the option "For Sale" to sell the land. Of cause the resident must be the owner of the land in order to sell it. Is the resident member of a group that owns the land, the resident must apply for the permission to sell it. The option "Allow Deed to Group" will be helpful here.
It is also possible to offer land directly to a group of residents or a single resident.
The desired price should be entered in the field and the option "Sell for L$" should be activated. If the resident want to offer the land exclusively to a resident, he can select his name with the function "select".
Further details in the book "Second Life: The Official Guide".