Creating SSL keys is pretty basic but I wrote it here not to forget it :)

Creating the keys

Use that command to create the key:

openssl req -new -nodes -days 365 -keyout domain.tld.key -out domain.tld.csr

Now openssl asks for the Information for the SSL Key:

Country Name (2 letter code) [AU]: DE
State or Province Name (full name) [Some-State]:
Locality Name (eg, city) []:
Organization Name (eg, company) [Internet Widgits Pty Ltd]:
Organizational Unit Name (eg, section) []:
Common Name (eg, YOUR name) []:www.domain.tld
Email Address []: you@domain.tld

Now you have an key and a csr file.