How Can I answer others' discussion?

I do not know why you cannot respond to a discussion. Maybe you can start new discussions first. When I first started I did not have any problems with answering to a discussions and I don't have ratings as well.

I think you've misread something. You can answer any discussion you want, you don't have to have a certain rating. You can't copy and paste until you get to 500 posts, though. Is that what you tried to do? I've written a couple of articles about myLot that may help you a bit. You can find the link on my profile. Welcome - and enjoy!