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If you’re signed into your Twitter account, this will load your feed. If you aren't logged in, enter your Twitter username (or email address) and password, and then click Log in . It’s at the top-right corner of the screen. You can also create a new tweet by clicking the "What’s Happening?" box at the top of the page.  To include an emoji in a reply to a tweet, click the speech bubble icon beneath the tweet you want to reply to. To include an emoji in a direct message, create a new message (or click a message in your inbox). It’s at the top-right corner of the tweet box. This opens the emoji panel. Use the category icons on the side of the emoji panel to view different types of emoji, then click the one you want to insert.  To find a specific emoji, you can type a keyword (such as “laugh” or “sad”) into the “Search for emoji” box. You can insert additional emoji the same way if you wish. This posts your tweet or comment you’re your emoji.  If you included an emoji in a reply to a tweet, click Reply  instead. If you are sending a direct message, click Send . If you want to add an emoji to profile information, here’s how:  Click the profile icon at the top-right corner and select Profile. Click Edit profile near the top-right corner of your tweets. Click the bio box where you'd like it to appear, then click the emoji icon to view and select an emoji. To add an emoji to the Name field, copy one from your bio by pressing  Ctrl+X (PC) or ⌘ Command+X (Mac), and then paste it into the name field by pressing Ctrl+V (PC) or ⌘ Command+V (Mac).  Click Save changes at the top-right corner of your profile to save.

Summary:
Go to https://www.twitter.com in a web browser. Click Tweet to create a new tweet. Click the smiling face icon. Click an emoji. Click Tweet. Add an emoji to your Twitter profile.