How do you say hello my name is alex What is yours in spanish?

One of two basic ways. Hola, me llamo Lexie. This is called a reflexive useage, and literally means "Hello, I call myself Lexie". It is translated normally as "My name is..".

The othe way is to say "Hola, mi nombre es Lexie." This literally is "Hello, my name is Lexie".

Either way works and is totally acceptable.