We have a Magento Site which is online. We want to change the theme. Is there any way to install a new theme, make changes on it, which it is visible only for us, and when it is ready to replace old with the new?
If you don't have a development environment you can always add a second
website to your installation, give it a random URL (don't use
/beta/, everybody does that) and set it to
noindex,nofollow under the
System > Configuration > Design tab.
Now you have a website you can install your theme on, make changes and when the time comes to switch either copy the settings to the live
website or inactivate the old one.
Side note: Please consider a development server. It's the best way to do stuff like this