OK. Thanks for this. I started a practice book, wrote the info, drew some tabs, and struggled to figure out the obvious and simple: that by fretting on the C 3rd string, I got C#, and continued fretting on that C string. I used my chromatic tuner to confirm I was on the correct line of reasoning. It is hard for my older brain to memorize (at almost 59 years of age), but I love the uke, and will stick to it! It is hard to remember that C# is also Db etc. Every day I work on it!