A blog is called un blogue in French. It’s a masculine noun.
The word blogue refers to the entire site, not the individual entries on the blog. For example, OffQc is un blogue, but the individual entry that you’re reading right now isn’t.
Some French words that can be used to describe the individual post you’re reading right now include un billet and un article. For example, you could refer to this post as billet numéro 602.
Posting an entry can be said in French as publier un billet or publier un article, for example: le billet que tu as publié, the entry that you posted.
The person that maintains the blog is le blogueur or la blogueuse. To spell these two words correctly, remember that both blogueur and blogueuse contain the root word blogue.
The verb form is bloguer, for example: je blogue, I blog.
publier un billet
publier un article
The spelling blogue (rather than blog) was proposed by the OQLF, and this spelling has since taken hold in Québec.