You should read some tutorials/resources about Scrapebox. Looplines Youtube channel has tons of video tutorials.
A little Info that may be the Issue with your comments,
1. They are not Auto Approve. You scraped 5k URL's, posted, but all of the blogs are moderated which need the site admin to accept the comment manually, or they are using an anti spam service such as Akismet, or Captcha Protection.
2. Your IP Is blacklisted by spam services. You're using your home PC, on what I'm assuming your home IP because you're new to Scrapebox. Proxies are really a must have for Scrapebox.
Those are the two Issues that come to mind.
The link posted by the user above also has some Scrapebox resources.