You must be a Super Administrator or Community Administrator to do this.
Navigate to your community by clicking hovering over the community icon (the globe) and clicking on your community's name under owned communities.
On the left navigation, click community settings > general settings.
You can fill out the information about your community here.
You can also add your organisation's branding; corporate colour, logo and a cover image. We suggest you follow this guide:
|Logo||150 (w) x 150 (h) px|
|Cover image||1920 (w) x 495 (h) px|
|About us description||200 characters max|