I can't use scrapebox properly...

scrape keywords for relevancy first. Use harvest to find blogs, check the page-source on a few of those URL's to spy on competitors, get other ppl's URL's (hint: use link:sitename in yahoo works awesome). Do this for 10-20+ of some of the other URL's you see on the same pages and you'll readily find other blogs that have approved this 'type' of comment. When you do a "link:" to get some of your competitors links, then do a "site:" on each of these URL's to get a crawl of all pages for all blogs that you've discovered so far.
starting with initial URL's on keyword crawl (after dup remove), then 10-20 competitor Link: harvest, (who knows HOW many thousands, remove dup domains, strip URL to root domain, then do site: on those domains). End up with 10-15k URL's. The lower PR of all this has made it all but worthless IMO, but you wanted to know how to do, so there ya go.
Personally: I'd rather take 5 upper-PR links that matter to THAT site's visitors, than arbitrarily spam 10k blogs lol
(if I can make suggestion, URL PR check is good way to do this, and then just visit the blog, read the article and comment if it makes sense to do so. These higher rank blogs actually get traffic, and if your comment makes sense to the article, is relevant, it will typically get approved. I tend NOT to use my Keyword as the name because it just feels less spammy and I seem to get btter approval. You'll also get the occasional clickthrough (sometimes lots) on these higher PR blogs, which you will practically NEVER see on the low PR blogs that get spammed to death. There's a right way and a wrong way to scrapebox, that's for sure. Most often it's not the tool, it's the user. Great for research though. Hope this helps.

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The real power of Scrapebox lies in optimized search footprints to find auto-approved, Hi-PR on topic links. Once you understand that, it is just a matter of scheduling scraping and posting