Please I want to update my software

Check the App Store for the most current version of WhatsApp. Depending on the version of iPhone you have and what iOS, that could be preventing you from getting a later version of WhatsApp. Check with WhatsApp Support to see why you cannot get the latest version you are expecting for their app. They are the ones that provide you with support for their 3rd party app.

So go to the App Store and update it.