Many users are familiar with traditional drive letters when it comes to saving Office documents. In some cases they struggle to understand the transition to UNC paths, navigating to web based locations or opening from a browser. To help them with this transition they can pin common SharePoint Online document locations to their favourite Office applications access menus.

Now, the traditional way to add a SharePoint location to an Office application was to locate to that location in SharePoint (i.e. a Document Library) and then select the Library tab in the top left. That revealed the Ribbon Menu. On this Ribbon Menu, towards the right, you would find the button Connect to Office. Selecting this would then map that location into your Office documents to make it easy to open those files directly.
Alas, from what I can determine this option doesn’t current work with SharePoint Online in Office 365. So here’s an alternative.

If I open Word on the desktop as shown above you can see that I am not currently logged into my Office 365 account. I do this by selecting the Sign in to get the most of Office in the top right.

I’ll now be prompted to enter my Office login details. I may also be prompted to enter my password if the system doesn’t recognise me.

Once I have logged in successfully, my identity will appear in the top right as shown.

Now when I go to open a document you see that I have already have my standard SharePoint Online Team site (Sites – CIAOPS here) and my personal OneDrive for Business (OneDrive – CIAOPS here). If I select my Team Site, on the right you’ll see a folder with your Team Site (in this case the folder CIAOPS).

If you select this folder, Windows Explorer will open and so you your normal SharePoint Team site (i.e. http://tenant-name.sharepoint.com, here http://ciaops365e1.sharepoint.com). So you can now navigate to the file that you need to open.
However, what happens if you need to regularly open a file from a completely different site collection you have created? That is, with a different URL from your normal Team Site?

Easy. Just select the Browse button and when Windows Explorer comes up change the URL in the path to be the one you want. In my case I have changed the URL to a completely separate Site Collection located at http://ciaops365e1.sharepoint.com/sites/test.
Navigate to the location you want to save and open a single file from there.

If you now navigate back to the Open location option in the Office application you should see the new location listed as above. To save this location so it can be reused to open files simply hover over the entry and you should see a push-pin at the right. Press this to ‘pin’ it there.

With the item pinned, every time you restart the Office application it will be there to allow you select files from there, even though, in this case, it is in a different Site Collection from the standard Team Site.