Android : Sending data from device (Android/iOS) to Server on Computer via Wi-Fi

I'm designing application for Android & iOS. I need to send some data to server on the computer via Wi-Fi. Data not heavy, just few strings and same response. Can anyone explain the way from Device.sendData() and Server.receiveData(). I need do it through url? If yes, so I probably need to rent hosting or how?

P.S. googled a lot before ask here. Will be thanksful for any advice and describing good practices!