Httpclient post to get securitytoken and then get request

Question

I have wep api  that requires

1) post a request with username and password to get security token

 when I ran through postman as

 post: myurladdress

body: {username: abc,password:password}

it return data with securitykey

2) then get request to get the result data

postman:  

Get: myurladdress2

Headers

content-type: application/json

securitykey: securitykey (this one is return from method 1)

 

this will give me desire data 

 how can I accomplish this in httpclient