go to admin->pages and hold your mouse over the button of your new page and you will see edit, click edit and put the link in the section for the page content.
something like:
<a href="http://some url" target="_blank">this is my page</a>
Sounds like you are trying to use the Oxwall mobile version. If you have a mobile ready theme then you do not need to use the mobile version and you can go to admin->mobile and disable the mobile version.
Then you can see your pages that you added on mobile as well as desktop. Then you can edit the pages and add the code i suggested above.
You can also try editing the mobile master pages of your theme.
You are doing it wrong, you dont create pages that way. You create pages under admin->pages->manage pages->add item
You put your button code in that page content section while your are creating the page.
see here
https://wiki.oxwall.com/faq:how-to-create-a-new-page-menu-item
then to see that page on the mobile menu just go to admin->mobile->settings and disable the oxwall mobile version.
As long as you have a mobile ready / responsive theme then you can see your new page.
If you have added your button code then you can see it and click on it.
Adding a new page also gives you the option to go to a remote page as well when you add it.
Now this is a bit different
If you want to add a external file to oxwall to run, like a prebuilt html file.. Then that is a bit different and see here how to do that...
https://wiki.oxwall.com/faq:how-to-add-external-custom-pages-to-oxwall
and here
https://developers.oxwall.com/forum/topic/47116
translate: what should be the code for a person from a mobile phone to open the page, go to the link and go to the mobile page, and not to the page with the words "this page is not available on the mobile version"
i created a custom page via mobile->mobile menus->drag and drop new page
however that new page for mobile does not show up in the menu (with mobile disabled) so you cant do it that way.
This is what i as trying to tell you, you cant do it that way.
2. create a page via pages and put your button code in that page content
3. pull up your site on your mobile phone and you will see your new page on the menu
As far as i know you cant add new pages to the mobile version like your trying to do.
as long as you have a mobile ready / responsive theme you dont need the mobile version, thats what im trying to tell you, just pretend the mobile version does not exist, it sucks anyway.
Just do everything via the desktop version and disable mobile version, all you need is a mobile ready responsive theme and it will work perfect for you just the way you want.
I believe the only way you are going to do that is to add some custom code to the mobile version part of oxwall. You would have to add php and html files to do what you want. Otherwise i dont see how you would do it, the oxwall mobile version is just too limited and does not work as one would like.
Anyone else want to chime in, correct me if i am wrong please.