Adding Widgets

I have a couple of questions, but I am trying to update the version of WordPress to 2.9, as well as add widgets to the Pixel theme. In addition, although it has been confirmed that I have write permission, I have made some changes in the code, but I could not save the changes that I made.

I have the widgets saved on my computer. The auto new install to the 2.9 version gives me a message that the installation failed. I also have questions regarding how to backup my files.

A novice that needs help.