When this is in place it's not necessary to individually specify where subdomains should point, as the "wildcard" directs all of them.
Wildcard DNS records can be added with A or CNAME records. You will need to add two records. The first one is an A record to direct the naked domain (e.g. mydomain.com). This determines where the domain points to, usually a website.
For this first A record you leave the Hostname blank (it will be filled in with @ once it's saved) and add your site's IP address (e.g. 18.104.22.168) in the Value field. TTL can be left as is at 3600.
The second record can be either an A or CNAME and includes the asterisk ( * ) as the wildcard in the Hostname field to specify that it directs all subdomains of the domain to the specified IP address or provided subdomain. E.g. *.mydomain.com would direct blog.mydomain.com, shop.mydomain.com, help.mydomain.com, and any others created to the same site or page.
It could be an IP address if an A record is used (e.g. 22.214.171.124), or it could be a specific page if a CNAME record is used (e.g. example.mydomain.com). Again, TTL is left as is at 3600.