multiple cores in oracle

Hello All ,

can i request couple of clarification related to the multi core please

I have system with 5 core server,

1)if five users / people logs into the server do we use multiple core ?

2) In the application if the users can open multiple orders at the same time in this case do we use multiple core or not.

It would  be great if you can provide me the link to the document from where i can find this information and also which helps to understand the multi core concept.

Thanks

Sankar