I need to upgrade Authorize.net module of magento 184.108.40.206, Please share the steps to do so.
In theory you could download the latest version of Magento and then take everything from app/code/core/Mage/Authorizenet. You will need to review what other files the extension uses, e.g. app/etc/modules, skin/ js/ app/design/frontend/base/default/layout and app/design/frontend/base/default/template.
In general, the recommendation would be to upgrade the entire Magento code base.