Create Post Request using java

Hi im trying to create a post request using parameters for an api, but the parameters are split into sections and i cant figure out if i should put them into sections because it isnt working when i use setRequestProperty("currency", "EUR"); all in on section but it doesnt seem to work.

{
  "endDate": "2018-07-18T22:59:59.000Z",
  "entryCriteria": {
    "allowMultiple": false,
    "amount": 0,
    "currency": "EUR",
    "markets": ["ie", "gb"]
  },
  "name": "channel All",
  "description": "",
  "startDate": "2018-07-17T23:00:00.000Z",
  "inviteOnly": false,
  "prize": "£0",
  "typeId": "594a3aac7f92197fac177901",
  "channel" : "All",
  "pickCriteria": {
      "minimumPicks": 4,
      "maximumPicks": 4,
      "pickTypes": ["FullTimeResult"]
  }
}