It's going to be rather difficult without acting classes. This is a skill like any other and not a lot of people are naturals. Even people who start off their careers without a lot of training will generally try to get some.
So, assuming there are no classes, what you CAN do is take some peripheral instruction. It usually helps to be able to sing and dance (you're more versatile that way, and therefore more likely to be hired), so see if you can take classes in both. Are there public speaking classes for people in business? That's another angle.
If you are in school otherwise (you don't say how old you are), you should also finish your education. Most actors and actresses take a while to break into the business. They wait tables, or model, or work in offices or construction or wherever they can make any money. And in the meantime, they need to live, so they need to understand their own finances, etc. Getting a good education can't possibly hurt you.