<input name="myusername" type="text" id="u" class="blackle u" value="Username..." />
<input name="mypassword" type="text" id="p" class="blackle p" value="Password..." />
Using jQuery...
Onfocus - if #u has val "Username..." then change it to "" (blank)
OnBlur - if #u has val "" (blank) then change it back to "Username..."
Onfocus - if #p has val "Password..." then change it to "" (blank) ; additionally here the val of attribute type should be changed to "password" from "text"...
OnBlur - if #u has val "" (blank) then change it back to "Password..." ; Again the val of type attribute should be changed back to "text" from "password"...