If you already have your SSL Certificate and just need to install it, see
SSL Certificate Installation :: BEA Weblogic 7 and older.
How to generate a CSR in BEA Weblogic Web Server
Start the Certificate Request Generator. This is done by entering the following into your web browser:
https://hostname:port/certificate
where hostname is the name designated for your server, and port is the number of the port for SSL connections.
A form will be loaded into your web browser. Input the information at each prompt, and click the 'Generate Request' button. (If any required fields are left blank, you will be so prompted by the servlet.)
The Certificate Request Generator servlet will the create three files:
yourdomain-key.der - the private key file
yourdomain-request.dem - the certificate request in binary format
yourdomain-request.pem - the certificate request in ASCII format
The last of the three files is the one to open and copy and paste into the DigiCert web form (including the BEGIN and END tags).
After you receive your SSL Certificate from DigiCert, you can install it.
See SSL Certificate Installation :: BEA Weblogic 7 and older.