Magento : How To Remove Back To School Block On Right Side That Comes Up After Checkout

Simple You can do by commenting the some codes in catalog.xml file by :
app\design\frontend\base\default\layout\catalog.xml
if you have installed any theme then according to that theme location :
app\design\frontend\default\yourtheme\layout\catalog.xml

Magento : List Of Prototype Javascript Validation Classes With Error Message

As U know there are some default classes in magento form field for validation.Like required-entry , validate-email ..etc.So I am here showing  to you all the default classes present in Magento (ver. 1.7.0.2) for  form validation .

Here Are Code To Get, Set, And Unset Session In Magento

Magento allows the functionality to set the the value into session and get it where you want and unset too.There are three different modules magento uses for handling the session variable.Most common is the core module for handling the session variable that is'core/session' .For using the session variable magento uses most favourable methods 'setter' and getter like to set session set(your variable name) and to retrieving the session get.So lets starts for more details how to use variable for set,get and unset session variables.