Regular Email Pop Up Mean?

I was just at a site where i wanted to enter a competition, and therefore had to send an email.I clicked on the 'send email' link, i received this message: you need to create an account before proceeding, would you like to create one now?'I clicked on 'yes' and was asked, 'what type of account would you like to create?' the choices being: regular email[pop]IMAP,news,import email opera web email[ i use the opera browser.The only one of those that i understand is the opera choice, so i clicked on that. That took me to my opera email account, i thought,fine.however, there was no sign of the email address that i need to be able to send them a message.now i'm sure you've come across this yourselves, it crops up for me every so often, when it does, it puts me off whatever i was trying to do, and i give up.what should i do? what does regular email[pop] mean?should i click on these other choices?why, when i click opera, am i not given the email address?