I can't configure a working redirect for a website

Well, I'm having this problem in setting a redirect for my web page to another.
I've my main domain where I can access from my cpanel account.
We can say myhomepage.com then I have another page on my server xxx.xxx.xxx.xxx.
I need to create a redirect to shop.myhomepage.com that is hosted at xxx.xxx.xxx.xxx.
The point is that I need to go to shop.myhompage.com, and the browser have to open me the xxx.xxx.xxx.xxx and it works. What I can't configure is that I want to see shop.myhomepage.com and not xxx.xxx.xxx.xxx in the address bar.

How can I mask it? I've already made the index.html as shown in some guide but nothing to do.

any advice?

thank you

 

well I've done it, it redirect with the alias but it's not masked, when I open the main domain shop.myhomepage.com it redirect me to xxx.xxx.xxx.xxx but I keep having the xxx.xxx.xxx.xxx in the address bar, while I need to have shop.myhomepage.com.
I can't find the option to mask it.