The engine, transmission, and clutch all use the same oil.
There is a filter on the sump plate, often torn, replace or patch.
There is a filter in the right side engine cover, seldom need replacing, just clean it and reinstall.
Do you have a repair manual? If not you should get one. It will be the most important tool you will ever own. It tells all about the basic maintainance on your bike and the not so basic.