How to upload a pdf file on one of my pages???

I am pretty sure you can do it through – media > add new.
Then add that file to the page through upload / insert.
You can also upload through upload/insert

Just like any other picture, too. I think the only thing you can′t to is directly inserting it to your post. But this works on my site:

<a href="https://www.yourdomain.com/wp-content/uploads/2012/04/file.pdf">Download PDF</a>.

Easier to do when you highlight the word(s) you want to be the link and then clicking the add link button in tinymce (Visual editor).

I′ve set the link to open _blank / in a new window because otherwise people would have to go back to view your site again.

edit: code glitch