Select Chore Chart from the At Home section

Click Make Your Own

Read the guide for making a skill using blueprint.

Set the members of the household and the chores or tasks that need to be carried out.
When finished click Next: Assign

Assign the tasks and schedule reminders for devices.
Make sure that you set reminders for all household members.
Note at this point you can still add users and chores.

You can now customise the messages that Alexa will say.
The intro section will be the message that is said when the skill starts.

You can then add extra message to encourage people when they hear their list of chores.

Keep working through all of the messages.
You can also customise the colour of the background that will appear if you are using the skill on an Echo Show or another device with a screen.

Finally you need to name your Alexa Skill
Click Create Skill and it will be enabled for your selected device.

Wait for the skill to be created.

Now go and chat to your device.