Hey guys. I am new here. I recently started playing oblivion. Now I am a level 2 custom class mage. But I cannot remember what were my governing attributes.

Does anyone know how to determine them?

Look in your Stats Menu, I think the number 1 pulls that up, or maybe it's F1, but for sure the tab key or on the console whatever button for that. Look for your skills list, Major skills should be listed first or marked in some way. My install of Oblivion is not ready to go yet, otherwise I would launch it...

It's the F1 key to bring it up I think.

IIRC it's the first seven attributes that's your major attributes, but you can also determine what major skills you have by just looking at the level of it and if the level is a little higher than the other skills then you can consider it to be a major skill.

Just to clarify: Are you talking about the 2 favoured attributes of your class, your 7 major skills or the governing attribute of a skill?

For the favoured attributes: They aren't specifically listed anywhere, but you can take a look at the attribute list in the menu (TAB- key). Favoured attributes get a +5 bonus. But that's also the only effect they have.
Major skills can be seen in the menu. They are listed above the rest of the skills.
Governing attributes of skills can also be seen in the menu.