I'm-new-to-SL-and-have-only-a-first-name-but-at-login-there-is-a-second-name-required??_

[VMelodyV]

I'm-new-to-SL-and-got-only-a-first-name.Now-at-login-the-second-name-is-also-required.But-I-have-none.-How-can-I-come-online-then?

Thanks

[Lindal Kidd]

For this purpose, your last name is "Resident".  Log in as VMelodyV Resident.

[Rolig Loon]

The last name "Resident" should only be necessary if you are using an old-style V1 viewer like Phoenix.  Those will be obsolete with in a few months, so I suggest switching to Linden Lab's V3, Firestorm, or another modern viewer.