Installing more than 1 blog on domain

I created a blog on base domain p.x. https://www.mydomain.com,
but i also created 2 more in the same domain.

I created the subdomains but the blogs cant work from
https://sub1.mydomain.com and https://sub2.mydomain.com
only when typing
https://www.mydomain.com/sub1 or https://www.mydomain.com/sub2

Do i need to add something on .htaccess file?

thanks