Step 1) Create a normal link (for more information read how to link to a page)

Step 2) Click "edit html" (for more information read how to edit your html)

Step 3) Find the code that looks like this:

<a href="pagetolinkto">Link Text</a>

Step 4) Add the code marked in bold bellow to the relevant place

<a href="blog" target="_blank">Link Text</a>

Step 5) Click update

Step 6) Publish your page

Your Done! Your link should now open up in a new window/tab

If you have any questions, then please just start a thread bellow this page.