In order to create a wildcard certificate first we need to generate a certificate singing request using below steps:

1. Make sure certificate authority service up and running in your server (If certificate authority is not installed, you can refer this to install it)
2. Navigate to IIS manager and select your root server.
3. Double click on Server Certificate under featured view.

4. Select “Create Certificate Request” under Actions from right hand section. Fill required information

Note: Make sure to use an asterisk (*) because we are creating wildcard certificate.

5. Click on Next and select below options
6. Cryptographic Service Provider: Microsoft RSA SChannel Cryptographic Provider Bit Length: 2048
7. Click next and specify file name for your certificate request for example (Let’s say wildcardcert)
8. Click on Finish
9. Now we have created a certificate signing request, we can submit it against windows certificate authority using below steps.
10. Run command prompt and use below command 

certreq-submit -attrib “CertificateTemplate: WebServer” c:\wildcardcert.txt    

12. First it will prompt to select certificate authority and then it will prompt to save your certificate, give it a name and save it. Exit from command prompt.
13. Now we will be completing our certificate request using complete certification request.
14. Goto IIS->Root server->Server Certification->Actions and select Complete Request option under Action.
15. Click on browse and select your certificate file that is created in last step.
16. Provide friendly name and click ok.
17. Now our wildcard certificate is ready and can be used in binding MS CRM website.