I've just put up a post with several url links. Here's how to do that:
First, you copy the url of the article you want to cite as indicated in the first image. Here I was on a blog called, The Frontal Cortex, and I wanted to comment on the "Why do some people learn faster" post.
Note, what you want to copy is called the permalink. The permalink includes the date and name of the post, and it will always take you back to the original post. Look for that option at the end of a post, though sometimes you can just click on the title of the post itself. If you copy just the blog url, over time, the post you want to highlight will be buried by more recent posts.
Then, as shown in the second screen, you click on the icon for inserting a link in the Create Entry screen. This produces the darkened screen with the active box for pasting your url. So you do that and click OK.
Back on the Create Entry screen, there is one thing that you have to get right for this to work. This is illustrated in the third image. You need to add a few words between what are called the "carrots"--the >< --in the code in order to create the link that readers will click to access the original source. Just look for the carrots in the code and add words, any words, between the ><.
The fourth screen shows what the previous screen looks like in Preview. In the Create Entry screen, I had two url links, one with and one without linking text. You can see in the Preview screen that the link without text is no longer visible. The text that I added is now highlighted in live link blue. When you save your post, this is what it will look like to your readers. If a reader clicks on the blue text, he or she will go to the article on which I was commenting.
So that's it. Very simple, really!