This is a nice try and virtually all Japanese-speakers would understand what you are trying to say.
If I were asked, however, whether or not that sentence was 100% natural-sounding, I would have to say 'no'.
It would be more natural if you used the verb form 「投稿しています」 if you have already been doing it even for a couple of days. This is indeed one of the biggest differences between real Japanese and Japanese-as-a-foreign-language.
I have seen/heard so many Japanese-learners say:
Native Japanese speakers, however, would invariably say:
The first sentence using 「します」 is grammatical, but it can sound like studying Japanese is something the speaker plans to do in the (near) future. It sounds like something said by a high school senior who is planning to study or major in Japanese in college.
Next, the 「日本の歴史,文化と神話について」 part is not necessarily incorrect or unnatural, but it can be improved a little. I would recommend: