"Pinging" your blog basically means that you have notified blog search engines that your blog has new content. Most how-to blogs will recommend this as a good way to get traffic. I have mixed feelings about pinging.
In order to ping your blog, I would recommend using a pinging service. Ping-o-Matic is a good one. All the available ping sites pretty much do the same thing and recommend your blog to the same list of blog search engines. You type in your blog's name and web address and then check off which places you would like to ping (or "notify").
In theory, you could ping as much as you want. But it would be a waste of time. It won't generate that much more traffic for you. Only ping when you have fresh content up on your blog.
Pinging does "work" in that it generates views for your blog. There's no question there. If you've had a blog for a few months and then you start to ping, you'll notice a traffic spike minutes later. While this is very exciting to see the first time you do it, most of the traffic is not good traffic.
Every time I ping I look at the referring site addresses sending traffic to my blog and it will usually be some spam site. Which tells me that hundreds of views I just got weren't really humans interested in reading my content and were probably just some automated data mining computer software. So the views are totally meaningless.
What pinging has helped with is keywords. After I started pinging, I noticed that places like Google have been picking up more and more on the keywords in my blog post rather than just what's in the title.
So, ping if you will. But I don't feel it's really crucial. Back in the early days of the internet I think it was much more effective which is probably why the pinging advice persists. These days there are just too many automated spam sites in place.