You’re able to enable Family Library Sharing to accomplish this. You’ll just need to login to your account one time on the second computer and enable Family Library Sharing. This will allow any account that signs in on the secondary computer to use your games with their own accounts. Sadly, this does not allow you to play simultaneously. That means you won’t be able to play multiplayer games together with a single copy.
Here’s some info on how to enable Family Library Sharing: https://support.steampowered.com/kb_article.php?ref=3784-QLBM-5731