Social media marketing

Hi I have two mobile fitness apps. One is already on the app store. But relseing the second one on January 2nd. Would like some to look after the social media side of things. Getting my likes on our pages, app Downloads and creating a buzz about the new app that's coming etc. Looking for so ming to this on a permanent bacis as we will be releasing two fitness app program a year. So would pay monthly or what works for you.