Simple enough to take a look at currents here on Earth and get an idea of how things work, then go ahead and plot those out on your map. Northern flows go clockwise, southern counter. Water from the equator heading south is warm and therefore warms the atmosphere and that brings moisture to eastern coasts, while western coasts are cool water. Then you figure out your air currents, the ITCZ and its meanderings... get the gist down and you can figure out a realistic enough climate fairly easily.

You could be a climatologist and the best you can really do is make it plausible so far as we understand now... its a complex system that we really don't have a complete grasp on in the world we live in, let alone one we construct, so make the generalities plausible and go from there, LOL.