I guess you mean you tried to leave comment on my blog page? I don't know how it works either ... just tried it out ...
- if you are logged into Google/ G+, you just write the comment and there you go ...
- if you are as above but want to be anonymous, you have to check "I'm not a robot" box before "publish".
- If you are not signed into Google/ G+, you have to check "not a bot" then click on some photos for G to confirm you really are not.
- there are other options, but those are too much even for me.
I'd switch all those off, if I only knew how to do it.