how do I lock the door and change house name?

[Amethyst Jetaime]

I assume you refer to a Linden home. Contact live chat to fix those problems.

 

[Amethyst Jetaime]

I assume you refer to a Linden home. Contact live chat to fix those problems.

 

[Rolig Loon]

As a footnote to Amethyst's correct answer, there is no such thing as a truly locked door in SL.  Locks are mostly decorative, to give you a sense of familiarity with the way things work in RL.  In SL, you can always teleport past any locked door, or simply sit on something on the other side.  If you are concerned about security, you can always erect ugly ban lines or invest in a scripted security system, and you can use the option in About Land to prevent people outside you parcel from seeing you.  Most experienced SL residents don't bother, though.