For general recommendations, see these discussions:

https://www.researchgate.net/post/I_have_submitted_my_thesis_the_question_is_can_I_published_the_chapter_of_my_theis_in_any_journal/1

https://www.researchgate.net/post/Publishing-your-thesis-as-a-book-and-also-publish-journal-articles/1

https://www.researchgate.net/post/How-to-turn-a-dissertation-into-a-book/1

https://www.researchgate.net/post/How_does_a_thesis_convert_into_a_book/1

https://www.researchgate.net/post/Which_is_the_best_publisher_to_publish_the_PhD_thesis/1

https://www.researchgate.net/post/I_want_to_publish_my_thesis_as_a_book_What_authentic_publishing_houses_do_you_recommend/1

https://www.researchgate.net/post/Who_can_provide_information_on_available_free_of_charge_academic_book_publishers_where_I_can_publish_my_dissertation/1

So also the following two discussions on how to publish papers (articles):

https://www.researchgate.net/post/What_are_the_procedures_for_publishing_a_research_paper/1

https://www.researchgate.net/post/For_publishing_article_in_any_journal_which_necessary_steps_should_be_taken_care_by_a_new_researcher/1

Finally, there is the possibility to upload your thesis to ResearchGate, but this will not be regarded as a publication. See this help page for instructions: https://help.researchgate.net/hc/en-us/articles/14293005132305-How-to-add-research

You find a journal you like then follow their guidelines :)