How do I get better at drinking?

When I was 15 I found my mom’s tiny whiskey bottle stash and drank about 6 of them for my first time. Needless to say that was not a good time and I stopped until I was about 19 and ever since then I just can’t drink. If I have alcohol I throw up about 10 minutes later for some reason. How do I overcome this to be able to actually handle a beer?