Yes, anyone can join the contest. Below is a link to our latest contest.
https://steemit.com/cookwithus/@cookwithus/cook-with-us-11-post-your-entry-here

All the rules for posting an entry are in that post. You will also find our calendar in that post so you can check out all the upcoming themes. We just started a discord channel too for chatting. If you have any questions about exactly how to enter let me know. And even if you make a mistake while posting we will let you know how to correct it and make the entry valid. Happens all the time!

The contest runs from Tuesday to Monday each week. Hope to see you there!