Calligraphy by Maître Taisen Deshimaru.
Zazen is very simple. However, you need to be guided in the practice by an experienced teacher. It is preferable therefore to practise in a dojo where the presence of others creates a strong atmosphere and where an authentic teaching can be given.
The temples, dojos and practice groups are open to anyone who is sincere and wishes to practise and harmonise with others.
There is probably a dojo near you (see Places of Practice). There, you will be able to participate in an introduction to the practice (see video) and do zazen with other members of the dojo.