Please Help Me with My Sub Domain.?

You need to create more CNAME records.

If you want dogs.yoursite.host.com to redirect to www.yoursite.host.com/dogs then you need to create a CNAME record to reflect that.

Your registrar should provide a control panel for this.

You probably already set up the www subdomain record. Now you just need to do the same thing for the rest.

Let's say your server IP is aaa.bbb.ccc.ddd

You would just then need to set a canonical name record that redirects:

dogs.yoursite.host.com to aaa.bbb.ccc.ddd/dogs

So you got a subdomain yoursite.host.com and you need to create a "Dogs" page?

If yes, then all you need to do is login to the FTP account of yoursite.host.com and create a "dog" directory. Then, upload your webfiles to the "dog" directory.

Unless there's already a "dog" directory on the account, going to yoursite.host.com/dog will give you 404 (cannot display page) errors.

Which web host are you with? You might have to ask them for FTP instructions.