Click on settings (top right) and then the Picturetab and browse for your desired picture.
You can't upload from Photobucket etc so make sure you have the picture saved to your computer.
You upload your picture on too twitter
Save your Facebook picture to your computer and then upload the file as your profile picture within the Twitter settings.
You click on upload a picture!
Most people use websites like www.twitpic.com to upload a picture and provide a link in their update.
Save a gif to your computer and upload it as your profile picture on Twitter.
You HAVE to have a Twitter and go to TwitPic and enter your twitter username and password on the top. But you must have pictures on your laptop or computer.
If you have a custom icon you can simply upload it where you would normally upload your display picture.
You can link to it in a tweet or upload the photo on TwitPic.
You go to edit profile, click browse and choose a picture from your computer .
Connect your iPod to your computer and download the pictures from your iPod to your hard drive. Then, sign in to TwitPic (or another online image host that supports Twitter) with your Twitter details and upload the picture.
The same way that you upload non-moving backgrounds. (Save the picture to your computer and upload it in the design settings)
You can create a "gif" through a computer program or on various online websites and then upload it in the same way you would upload a normal picture.