Can you please tell me how can I make a simple connection with remote db in android app? Basically, I want to save users names, emails etc. in a remote database and retrieve
I guess you could use common Java libraries to create a connection to a database. But you are working on a mobile device, this means that you have to work with constant connection interruptions etc. A database connection that is opened for a longer time can be difficult with this kind of network issues.
I would suggest to have a simple (maybe REST based) web service that lets you provide the input to the db via a simple short lived http request.