How to show the popup on click of a button

Hi,

I am trying to figure out if there is a way to show the login/register popup on a click of a button in a post and when user logs in, that login button (to show the popup) should hide and another button to download some file should appear.

So basically if user is not loggedinm he should see the button to get the login popup and if he is logged in, he should see some other button to download some file from my website.

Thanks.