I'm finding the names difficult and can only think that they that they are shortened versions of proper names, at any rate they are both female names.
Meine liebe (Meta?)
Bei meinem gestrigen Brief hab ich ganz vergessen noch einmal Deiner zu erwähnen. Wir halten es als selbstverständlich, daß die Einladung auch für Dich mitgeht. Grüß Deine Eltern nur recht herzlich von mir ich ließe herzlich bitten, daß sie Dich herreisen lassen.
Deine (Berten?)
My dear Meta
In my letter of yesterday I quite forgot to mention you again. Of course it's taken for granted that the invitation included you. Send my warmest regards to your parents and tell them that I earnestly request that they will allow you to travel here.
Your (Berten)
Tried to make the last name into Berta, but I can't see it.
The card is also addressed to Meta, I think..Fräulein Meta Struve
Address - Uetersen/F (the F should really stand for something like a river name, but the nearest rivers are the Pinnau and the Elbe)
Kühlenstr. 22 (str. short for Straße = street)
Since the writer uses the familiar form of address, you can assume that Meta at least is either a young girl or that these are friends or family members.
Hope someone else can solve the mystery of the names.
Gillg
The postmark appears to be Lübeck, although the L is missing. Can't decipher a date, though.