Q: i have an ipad 2 with ios 4.3.3 and i really want to make the backuo. please help me

Hi ..

Update your iPad iOS software to 8.1.2 then try a backup.

You can update via a Wi-Fi network right on the iPad by tapping Settings > General > Software Update

Or using iTunes >  Update the iOS software on your iPhone, iPad, or iPod touch - Apple Support

You cannot update to 8.1.2. You will have to update to 9.3.5 as Apple only allows you to update to the latest iOS supported by your device and the iPad 2 supports 9.3.5

You don't need to update at all to backup.  If you want to update your iPad 2 can in fact update all the way to iOS 9.

To Backup, simply plug your iPad to your computer using its USB cable, and in iTunes click on the backup button.

Follow the steps in the following support document in the section for iTunes:

How to back up your iPhone, iPad, and iPod touch - Apple Support

For help with an iTunes backup.

If your iTunes backup couldn't be completed or you can't restore from a backup - Apple Support

For help with an iCloud backup

If iCloud Backup couldn’t be completed or you can’t restore - Apple Support