I always find this terminology confusing. We have a blog inside of WA, which operates by a stricter set of rules. We have our own external websites which are "also" blogs, and plenty of people use the word blog and don't specify which they are talking about.

If you are referring to the WA internal blog, this is mainly for connecting with and informing other WA members of your progress, or whatever you want to write about, but it should not be a repeat of what you say on your external website.

In fact, you're not supposed to even link to your external website from the WA blog. You can link to your website and/ or social media on your profile page, and there are specific threads where you post articles you want comments on, but otherwise you don't promote your website on your WA blog or anywhere else on WA.

We are also not supposed to write about politics, religion, or any other controversial topic here in our internal WA blog. However, whatever you want on your external website, which you own.

If you're talking about an external blog website which you want to move to a WA-hosted server, then Lawrence's answer applies.

I hope this is helpful.

It depends on what platform your existing blog was created on.

If your existing blog is a WordPress Site, then you are absolutely fine.

You have multiple options with Wordpress sites, including moving it to be hosted here or pointing the nameservers here, which I would recommend.

If your existing blog is not a wordpress site then you can still do the training (or at least the majority of it) and use the community (which is well worth it) but you lose out on the use of a lot of the other benefits that you are getting for your membership.

i.e.
secure and fast hosting
SiteComments
SiteFeedback
SiteManager
and SiteSupport (which is second to none in my view)