Building a mobile app

Hello there, My name is Maya and i live in Zambia and have been learning code this year, but have not gotten to a point where i can create the app i want to create and have running by march 22, 2018. Therefore, i have decided to implore some help in order to reach my goal and quite possibly learn some new things along the way. I am working on a fairly small budget, but i am open to negotiable offers. So i am basically trying to create an app that is similar to the app called 'Depop' (which is a platform and hybrid between instagram and ebay, where people in the Uk (recently opened to other parts of Europe and US) can display their clothing that they either bought and never wore, or wore a few times or for some reason they no longer want them.) The clothes displayed can be liked and favorited and customers or prospective buyers are able to contact the vendor through private message and or correspond with them through the comment section of the particular subject item. I want to start on a small scale where young adults can create accounts and upload pictures of their merchandise which can then be bought by fellow youth and so on (It is quite pivotal to have a look at the Depop app and its layout in order to see my vision) I have been thinking about a name but have not come up with one catchy enough yet. I expect to launch this app only in Zambia (Southern central Africa) for the use of young zambians perhaps starting with one city and then possibly expanding outwards to other surrounding cities.