The Weidian desktop page is only available in Chinese, however there's good software, for instance the built-in google translate feature of chrome, that can translate the page in real time.
For mobile however, you don't have this capability, and thus there's no way to use the Weidian smartphone app in English. Sorry!
As I mentioned, if you have to use native Weidian, use the desktop version on chrome, but if you just want to buy something, which I bet is the case, you never have to visit Weidian. You can just use your agent and paste the link.