Who was Eriol?

Hi

Im a newcomer and I think my question should be posted in this section.

I just want to ask if someone can give me a short background on the storyteller Eriol. I just started to read the book of lost tales II. From reading the Silmarillion I like the stories included in book lost tales II better then the ones included in book of lost tales I and therefore I didn’t start with no I. Since Eriol is just introduced as a "known" character in book lost tales II, I want to ask some things. For example, how did he come to Tol Eresssa? why did he go there? In what age is this mariner living and other interesting things about him.

/the ignorant Cave troll