1) if you are referring to EJB 2.0 components, you don't have to worry, EJB 3.0 is backwards compatible and supports entity beans, for example.
2) post your code and stack trace. look at the seam example projects code.
Thanks for your response.
I have another question.
Is it necessary during building of Seam project create .ear file, or I can just create .jar and .war files and deployment will be fine???
Thanks in advance.
An EAR contains wrapped WARs and JARs, a WAR is standalone.
I recommend sticking with the seam-gen (or JBoss Tools) generated project until you are comfortable with the packaging formats.