How can i get data from web API with my json data?

Hello!

I have api, https://site.com/api

I have json data that I need to run the query:

{
  "aggs": {
    "round_aggs": {
      "terms": {
        "field": "host.hostname.keyword",
        "size": 2000
      }
    }
  },
  "size": 0
}

How can i get data from web API with my json data?

i have this example:

let
Json = Json.FromValue({[idType= "ID_ISIN", idValue= "US4592001014"], [idType = "ID_WERTPAPIER", idValue = "851399", exchCode = "US" ]}),
Source = Json.Document(Web.Contents("https://api.openfigi.com/v1/mapping?", [Headers=[#"Content-Type"="application/json"], Content=Json]))
in
Source

But I don't know how to do this with my json data

Thanks in advance