One site two blogs

I’m setting up one site with two blogs, with two installs of WP. I have
the domain name example.com
First WP install at is at example/install_1
Second WP install is at at example/install_2
I have pointed the domain name to example/install_1
Site works fine with static homepage, and blog 1 works

Question: how do I handle install_02
How do I login to the Dashboard of install_02, do I have to create another domain name to do so?
Otherwise how do I post to blog 2 and how do I view blog 2 from the install_1 website.