You will usually need to have at least 1 diary for seed companies to accept your application for competition. So get a seed, document your grow. Take 1 creative photo a month enter photo of the month contest. And when it's done enter newbie of the month
they want a few finished gow journals, typically, before they send you free seeds.
take good pictures, play nice with others (oops, i failed twice!) and you'll keep getting free seeds.
Most contests on the contest page will have a link to a google form or something similar that you have to fill out with your information and then they will email you back. Usually, you can also get the seeds yourself and join the contests directly too if you end up not getting in through applying - although from what I've seen as long as you have some journals to show then you'll usually get in.