That's how I started with logons, asking other people if I could use their wallpapers for a logon, and it's true, most people will say yes.
I started with pretty basic Logon Studio logons, and asked some of the people here, and Deviant Art too,to use their wallpapers, and they said yes.
And the more practice you get at making them, more people will let you use their walls until you learn how to make your own. It just takes time and learning.
I suggest you stay with Logon Studio for awhile, learn how to do them well, make your own graphics as you learn how, and when you get comfortable with your graphics skills, then maybe think about trying more complicated logons.
And if you have questions or problems with Logon Studio, just email me: boss0192002@yahoo.com.
Also, Cavan is very good at Logon Studio logons. Look him up...he's really helpful too!

Just remember if someone gives you permission to use their wallpaper for a logon...include a permission text in the logon and give them credit in your description and a link to their page.