<
jsp:setName name="username" property="*" />
Tag is <jsp:setProperty> & not <jsp:setName> & hence the confusion.
name="username" refers to id attribute in <jsp:useBean> tag which would be there, perhaps at the start of the page, so i suggest have a closer look at it & then read next stuff
if i correct the tag as <jsp:setProperty> instead of <jsp:setName> meaning is set all ('*' means all) the properties of javabean who's id is "username" specified in <jsp:useBean> tag.
In <jsp:useBean> tag you will find following attributes:
id--unique id for a JAvabean (Actually its a reference name)
class--fully qualified Classname of Javabean (i.e. including package name)
scope--scope of Specified java bean
Web container will instantiate JavaBean & reference (name Specified in "id" attribute will be pointing to that object)
I hope this helps..Otherwise feel free to throw more questions...
Shriniwas