Adding a button to a Snap

Dear Experts

I am now in developing Snaps. I am trying to create an Account Snap with works similarly to the REST Snap. I am however struggling with the following points:

• How can I add a button to the UI (Similar to the “Authorize” button in the Rest Snap).
• Is there an easy way to redirect/pop up a login page after one has pressed this button.

Thanks in advance for your tips.