Layoff happened 18 days ago, feeling lost - any advice?

I lost my job as a procurement assistant and I am not sure what to do first. I am in Honolulu, in case local advice matters. I have a box of my things and a short letter about benefits. Which steps were urgent?

Thanks for writing this out. I went through something close to it last year, and it got easier once I kept a simple log of every call and form.