How to Block Robots

I’m using the latest version of WP that’s not listed in the “Version” box …

While I’m working on the design of my websites, I don’t want any visitors of any kind, except for me. I’ve browsed some older posts in the support forum on this, but I’m not finding anything current with specific information on how to do this. Other blogging platforms I’ve used have offered privacy features that password-protect websites from being accessed, but I’m not sure that such a feature would block out robots and prevent my websites from being indexed.

In layman terms (go easy on the old Moose), how can I accomplish this task? My Google searches bring up tons of posts on this topic, but I’m not understanding how to do this from WP.

Thanks!