A flow consists of nodes and edges (or just nodes). Together we call them elements. You can pass a set of elements as a prop to the ReactFlow component. A simple flow could look like this:
import React from 'react';
import ReactFlow from 'react-flow-renderer';
const elements = [
{ id: '1', type: 'input', data: { label: 'Node 1' }, position: { x: 250, y: 5 } },
{ id: '2', data: { label: <div>Node 2</div> }, position: { x: 100, y: 100 } },
{ id: 'e1-2', source: '1', target: '2', animated: true },
];
export default () => <ReactFlow elements={elements} />;