I wrote those instructions with picture references for a client a while back and though it might be helpful for you as well
You will need:
Lens Studio Installed on your Laptop/computer
A Snapchat account
1: Open the project by double clicking on the Lens Studio File in your Project folder
2: Open ‘Project Info’
3: Give your Lens a Name, a Lens Preview Video and a Icon
4: You can pick a preview video from the selection or upload your own
Note: If you pick your own preview video, you might have to change the size and aspect ratio of the video to be able to use it as a Lens Preview Video.
APPLY your changes and close the ‘Project Info’ Window
5: Click now on the ‘Publish Lens’ button
This will open a window in your browser
You will be asked to log in with your Snapchat account
6: After you successfully logged into your account, you can press the button ‘Submit New Lens’
7: A new Window will pop open to add some more information.
Lens Tags: basically like hashtags to find the filter easier
Scan Trigger: Person for Humans, Cat/Animals for Animals You can pick several.
Visibility: You can change the visibility anytime even after the filter has been approved by Snapchat on your profile.
Click ‘Submit Lens’
Usually, Snapchat approves Filters within 30min.
8: To find back your Lens, open lens studio, click on ‘My Lenses’