Becoming a Shinto adherent?

I've had an interest in Japan for a long time now, and began to read about the Shinto religion. It feels like a religion for me, and I am thinking about becoming an adherent.
But, I need more fact about it. I would like to talk to a Shinto priest, but my problem is that I live in Sweden, and I doubt there are any Shinto priests here.
Is there anyone who can tell me where I should turn to to get answers?
Very thankful for any answer.

Unless you want to become a priest, there is no need to join Shinto. It is different from Western religions where you become a member, pay fees and have an initiation ritual. Do like the Japanese do and visit a shrine and follow the rituals.
The Shinto shrine in Amsterdam is probably closest to you.

I know that I don't have to join it like Western religions, but I want to know more about it, to be a shintoist...

If you live in Sweden, you may have better access by meeting Sammi people.

As a Shinto/Buddhist follower and familiar with other indigenous beliefs and practices, most Native 'religions' have similar principles and beliefs (not the same but similar). Being in balance with nature, taking care of nature, purification rites, etc.

As long as you are sincere and seeking knowledge "in a good way" (American Indian phrase), you should be accepted in time.

It's a process and takes patience developing relationships.

I would like to become a shinto priestess. How are they about letting non-japanese in?

It's not impossible to become a Miko (shrine maiden) or Kannushi (priest, male or female) if you are non-Japanese, but it is tough. To pull it off you have to speak, read, and write Japanese fluently among a host of other things. You can also contact some of the Shinto shrines that exist in North America and Europe. Tsubaki Jinja of America, located near Seattle, Washington, USA, is a good place to start.

Does the shinto religion have any tenants?

Do you mean tenants, as in people who rent accommodation from a landlord, or tenets, as in rules or instructions to be followed by adherents?

Yeah I mean tenets that are rules that adherents follow.

Have a look at Wikipedia's page on Shinto, especially the "practices and teachings" section, or any of the hundreds of other pages on Shinto that come up when you do an online search.

Usually the shinto priests are from the priest family for generations, but if not, you will have to graduate from the university specializing in shintoism such as Kokugakuin University or Kougakukan University, and then be trained at the headquarters of the shinto shrines in Tokyo to be qualified as a shinto priest.
You will have to understand Japanese classics to study shinto and chant congratulatory addresses.
Unlike Christianity, shinto is our indigenous religeon, deeply permeating through the spirit of the Japanese for many many centuries. Also, shinto do not preach people but we know somehow the importance of living and thinking in the shinto way.
I am happy to know that you like shinto, so I recommend you to visit Japan first and experience the Japanese culture and customs as well as to visit shinto shrines(there are 80,000 shrines throughout the country). The most important shrine among them is Ise Shrine in Mie prefecture where our sun deity(Amaterasu-oomikami), the ancestor of the emperor, is enshrined, and Izumo-Taisha in Shimane comes second.
It may be nice for you if you can feel the special energy at the shrines.