In my opinion,maybe you have to start with the greeting,such as good morning or good afternoon,it depend on the time when you will talk about.for the others is good.you just write the introduction of your name like "I am XXX" it is fine if you introduce like that.I will just write an example:
Good morning everyone,I am XXX.I come from Shenzhen,I'm now 18 years old,my height is one hundred and sixty seven meters,I weigh 54 kg.I'm a smart and sanguine girl.I am also good at singing,dancing and playing piano.