Every wallet has one public profile. Open Command Center, then Edit profile, or press Edit on your own profile. You can set a picture, a banner, a display name, an @username, a bio of up to 280 characters, and links to your website, X and Telegram.
Press Save profile. Your wallet signs a message to prove it is you. This is not a transaction and costs no fee. Without a picture, your profile shows the default green operative.