How to obtain a JWT token by calling the Login end-point

Hello,
I am trying to evaluate functionality of management api with my trial hosted mender account.
My first step is to generate personal access token from here: Mender
And then use the following command to request a JWT token and got a error message:

curl -X POST https://hosted.mender.io/api/management/v1/useradm/auth/login
-H ‘Content-Type: application/json’
-H ‘Accept: application/jwt’
-H ‘Authorization: Basic eyJhbGciOiJ…’
{“error”:“invalid or missing auth header”,“request_id”:“d64f60d1-5f2c-499b-a52e-41e4518f89dc”}%

From the instructions here : Mender API docs
The api needs to accept user credentials via standard Basic Auth. Would you pleaes explain more about how to finish the standard Basic Auth? Thank your.

Best Regards,
Jason