I found this tip in www.dreamydonkey.com .
1.Login to your dashboard--> layout- ->Page Elements
2.Click on 'Add a Gadget'.
Note : Remember to replace YOURBLOG with your real blog name.Also you can change below values.
No. of posts to be displayed nMaxPosts = your value
Scroll delay nScrollDelay = your value
Direction of scroll sDirection="left" or "right"
Character after each post passing sBulletChar="Any character"
Open link in new window sOpenLinkLocation="N" or "Y"
Now you are done.