Unity 5.5 Swimming Motion?

Hello all! I'm a student, currently working on a Final Year Project and am incredibly new to Unity. I'm trying to do an underwater scene and I have the fog, particles, bubbles etc figured out, but I cannot seem to grasp hold on how to make the FPScontroller have a swimming motion. I've tried searching up tutorials but the scripts I've found are for older versions of Unity and from what I understand, Unity 5 is different from the older versions so many of the scripts don't work. I have tried both Javascript and C# script and no, I do not have any background on programming at all. If anyone could give me a general direction on how to go around this or help out with the scripting, I would really appreciate it! Thank you!