How to select data from Elasticsearch from Grafana?

Grafana Elasticsearch
1

I have loaded some data from Sybase ASE into Elasticsearch and the data is as follows:
{
inst_name: ABC_123
sampletime: Jun 25th 2018, 08:48:19
connections: 456
}
{
inst_name: ABC_123
sampletime: Jun 26th 2018, 08:48:19
connections: 700
}

May I know the way of dashbroad setup at Grafana at Singlestat?
I have no idea how the query setting?

Please help.