Hi Noreen,
I suppose it is going to come down to what tools your hosting company has given you, or the type of FTP software you are using.
I either use software from my hosting company called Dotnetpanel. In there I can select all of my files and zip them into a zip file I leave in the root "wwwroot" folder. If during an upgrade things go pear shaped, I can delete the install files (except the backup zip file) and restore. All I do there is highlight the zip file and click on an unzip button in the toolbar provided.
Othewise, I use an FTP software program called WS_FTP Pro to view my local pc on the left for example, and the root folder of my website in the right side. Just highlight all the files and folders on the right, and copy over to the left. 20min later I have a local copy of all of my files backed up.
I also use Dotnetpanel to backup my database and also copy that to my local pc and on to a RAID1 backup server for regular archiving for several websites I have running etc... Works well for me anyway
.
I do have some free upgrade tutorials here...
http://www.tutorialzonline.com/Courses/tabid/56/Default.aspx
Just follow the links to the installation tutorials. I hope that helps you.
Cheers,
Trev.