Actually both is it different for a page and a post. Sorry I am a newbie to this

Go in a post/page and type the link onto the page. Then, highlight the link, and click the "add link" button on the tools menu.
You will have the option in the window if you want the link to open in a new page or not. That's up to you.

are you wanting to add links into your blog post?

Hi, Where do you want to add a link?
-a post?
-a Page?

In a post
1. Edit post
2. On the status bar under add media there is a link button "insert link"