In order to view a collection after it's been created, you must mint an NFT in that collection. It will become visible on your profile. Then, you'll be able to click Edit Collection on the left-hand side to access the management tools sidebar. All collection elements can be changed; minted NFTs cannot.
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Collection Title, Description, and URL can be changed as often as you like. Keep in mind that your URL must be unique, so may have been taken by another creator.
Assets
Collection Banner
The collection banner sits at the top of your collection page. Collection banners can only be static images.
Dimensions: 3x1; 1500x500px minimum
Size: 5MB max
Collection Avatar
Your collection can have its own avatar, separate from your profile avatar or icon. It displays as a hexagon in the left-sidebar. Collection avatars can be static images or gif/webp files.
Dimensions: 1:1, 500px minimum
Size: 5MB max
Collection Tile
Also referred to as the cover or thumbnail, your collection tile displays on your profile and the explore page as a static image or gif/webp animation. In the collection management tools the tile appears in white on the upper right corner.
Dimensions: 5x7; 500x700 recommended
Size: 5MB max
Links
Links to social media or external creator websites can be added to the Collection sidebar. NFTs and collections cannot be minted or created with URLs or email addresses in their descriptions or they will be flagged as spam.
To add non-social links, click + Add More Links. (Don't forget the http://)