This article will detail how to share your calendar so that others may edit the events on your own calendar. Note that this is one way access. If you want to be able to edit someone else's calendar they also must follow these steps.
First bring up your calendar in a tab, then look for your name on the left side where it says "My Calendars" it should look like this, but with your name.
Hovering over your name will give you the three dots to click, this will bring up a new drop-down menu, one of which is "Settings and sharing"
Clicking this will bring you to a new screen, where you'll get a multitude of new options on the left. You'll be looking for your name, then under that, "Share with specific people"
You may need to click the drop-down arrow by your name to show these settings. Once you click that it will automatically scroll the screen to this option.
From there click the "ADD PEOPLE" under your email. This will bring up a pop-up which will allow you to add the people you want. In this case I've added John as a test, but you can add multiple people at a time.
At this point you need to change their permissions, it's default is "See all event details" which is where they can see your calendar, but not edit it. You'll need to click in the box to bring up a drop-down to see the other options. You'll need to change this to "Make changes to events" if you want them to be able to edit your events! I don't recommend the last setting as it allows that person to share your calendar to others, only do this if you need this feature!
Once you're satisfied, just hit the blue "SEND" button, this will send an email to the people selected letting them know you've shared your calendar.
Keep in mind you can add and remove people all you want, but this gives them access to edit every event on your calendar, if you want them to just be able to edit only a few events, just add them to those events as a guest and allow guests to make changes.