Assuming that you are using the latest image of HassIO which is powered by HassOS then if you follow the guide https://www.home-assistant.io/hassio/installation/ this will get you going.
I created my config direct on the SD Card as per the instructions under Bullet No 3 sub bullet 2. If you follow the how to link it provides a generic configuration. Note if you do it this way you will have to mount the SD card on a computer. You can copy and paste this direct into your config file, and then change the relevant section from auto to manaul for static IPs.
My config file looks something like the following for a static ethernet connection
[connection]
id=my-network
uuid=d55162b4-6152-4310-9312-8f4c54d86afa
type=802-3-ethernet[ipv4]
method=manual
address=192.168.1.111/24;192.168.1.1
dns=8.8.8.8;8.8.4.4;[ipv6]
addr-gen-mode=stable-privacy
method=auto
For the static address (in the IPV4 block) the first IP range followed by /24 will be your chosen static IP, the second IP is your routers gateway address.