Before anything, text your family and ask them what time you were born. This type of thing doesn’t work unless you know the exact minute and hour you blessed this beautiful planet!
Next, find a website that can help you calculate it! I like https://astro.cafeastrology.com/natal.php especially since it’s straight to the point, and even describes the meanings behind your time of birth!
Here’s an example of mine:
As you can see, my birthday is in December; and I knew I was a Capricorn, so that’s nothing new.
It can seem really overwhelming, but it’s actually really easy to understand! Especially since the website itself explains every little thing,
Have fun getting to know yourself better, and if you want some more recommendations, look up ‘Co-Star’ and ‘The Pattern’ on the app store, they also calculate your birth chart and send you daily notifications based on it.