Blogger adds for you the alt="" tag when you upload a photo. It is wise to add alternative text to the alt= tag. Search engines cannot read photos. To do this you simply put alt="Text to describe the photo" in the img tag. Also, if for some reason, your visitor's browser cannot display the photo, the text is displayed instead of an empty box.

What I do is I highlight a portion of alt="some text", namely t="some text", copy then paste just before the last /". Add a space, then complete title="some text". 

Now when someone hovers their mouse over the photo, a tooltip will appear showing the alt attribute text.  If you are using opera, you may see some extra stuff.

Update 3 June 2008: If the above is not clear or you want more information, please refer to

Importance of alt="" and title="" attributes in HTML codes for images
.

If you face any problems, leave a comment outlining the problem. 

Peter Blog*Star
Blogger Tips and Tricks