First of all, kudos to you for taking care of your vehicle and checking the fluid levels! The bad news is milky oil can be the sign of a leaking head gasket or an even more severe issue, so you should visit a mechanic.
To fix milky oil in your engine, the engine needs to be flushed out with flushing oil. The head gasket and other components also need to be examined for damage, which is why you should get the vehicle professionally serviced.
However, if the vehicle has been stationary for an extended period or used sparingly, the milky oil could be occurring due to condensation in the engine. If you think this might be the case, you should go for a 30 to 60-minute drive on the highway, which will cause the moisture to evaporate. If the issue persists after a few of these drives, you should visit a mechanic.