Depends whether your ISP is a LIR or not. When they are they can get the IPs in ranges at their local RIR (RIPE, ARIN, etc.). They pay a yearly fee depending on the amount of IPs they have. If they are not a LIR, they probably use ranges owned by another LIR.
You cannot create your own IPs. You can however use internal ranges (not accessible from the Internet, eg. 192.168.0.0/16. 10.0.0.0/8, etc.).