How to get a job offer from an Icelandic employer

Hello,
I am 22 years old and I am an optometrist graduate from one of Iran universities.
Due to some major reasons I have been considering immigration as an option for some times but there remains a lot of unanswered questions, I wish you nice people could help me through.
My main concern is where and how to find a job offer? I mean are there any special organizations or websites that I can find job offers and employers? If so, would you please introduce some of them to me.
And then, do I need to know Icelandic for a job permit before I can come to the nation or English will suffice?
Any kind of assistance will be of high value to me.
My best regards

Welcome to the forum

Language would be a problem so you need to first learn it.  For jobs there may be websites or employment agencies that you can contact.

You could also find out details for optometrists in Iceland and contact them directly. You may have to undertake an examination to be able to practice in Iceland.  This examis likely to include language.

Thank you sir for youe reply
I now have an outline of the process, but for a deeper level of information, do you know any agencies in Iceland that I can contact to find out whether there are any jobs for my major?
If you do, please let me know.

Google is your friend.