How to integrate 2checkout with reactjs and nodejs?

I am trying to integrate 2checkout API in my reactjs &nodejs project.I reffered the documents which 2co provided.I created an account and in that webhooks&API i have "Merchant Code" and "Secret Key" but there is no "Publishable key" and "Private Key" Why?

what i have is:

             render = () => {
             return(
              <form id="myCCForm" onSubmit={this.Submit}>
                        <input
                          id="token"
                          name="token"
                          type="hidden"
                          value=""
                        ></input>
                        <div>
                          <label>
                            <span>Card Number</span>
                          </label>
                          <input
                            id="ccNo"
                            type="text"
                            size="20"
                            value=""
                            autocomplete="off"
                            required
                          />
                        </div>
                        <div>
                          <label>
                            <span>Expiration Date (MM/YYYY)</span>
                          </label>
                          <input
                            type="text"
                            size="2"
                            id="expMonth"
                            required
                          ></input>
                          <span> / </span>
                          <input
                            type="text"
                            size="2"
                            id="expYear"
                            required
                          ></input>
                        </div>
                        <div>
                          <label>
                            <span>CVC</span>
                          </label>
                          <input
                            id="cvv"
                            size="4"
                            type="text"
                            value=""
                            autocomplete="off"
                            required
                          ></input>
                        </div>
                        <input type="submit" value="Submit Payment"></input>
                      </form>
                     )}
  
             submit=()=>{
                   let args = {
                   sellerId: "",//gave merchant code here
                   publishableKey: "",//as there is no publishable key  what will give here?
                   ccNo: "",
                   cvv: "",
                   expMonth: "",
                   expYear: ""
                };

             window.TCO.loadPubKey("sandbox", () => {
             window.TCO.requestToken(args).then(data => {
                console.log("data");
              });
              });

How can i resolve this problem?