The Ukulele's standard "C" tuning is 4 notes higher - two steps GCEA
That's what I get for typing at 3:30 am.... The standard tuning is 5 notes higher - three steps, or a "third".
Other folks have good advice. Remember that you aren't transposing the
Chord, you're simply using a different shape to get that chord.
If you are used to playing a song on a guitar in G, using G, C, and D (The I/IV/V I mentioned earlier), then you will continue to play that song in G on the ukulele, but you will use different shapes. I think of it as rotating 45 degrees. The C chord on a ukulele uses what I spent 40 years calling the "G" shape on the guitar. In Uke tab, it is 0232. C on a uke is 0003, and D is 2220. These are, of course, simple first position chords. (I also want to point out that I have an absolutely terrible time
attempting to read guitar or banjo tab - but I'm starting to understand Uke tab. Go figure.)
One of the uke books ( The Fretboard Roadmap) is very good, in that it tries to get you to understand where the notes are, rather than relying on the shapes for names, and works in using concepts such as "the circle of fifths". Now, I don't pretend to understand everything Fred Sokolaw says in that book, but I realized I've been doing a lot of what he advocates over the years, when improvising, or joining a group of players - or even playing along with the radio (now the YouTube videos....).
I'll agree with Ukulele JJ - a ukulele chord chart is a great place to start - that's how I started on Guitar. But as you play, finding sheet music with different chords and forms (some of which I still can't find in the chord charts!) is a great help.
I can also recommend the Dr. Uke web site
www.doctoruke.com as a great site, lots of songs, some audio files, some videos, and many lessons.
So good luck, Zeke. Keep on Ukin'!
-Kurt