Create topic with Discourse API

Hello
I need your help please.
I’m trying to create a topic using Discourse API but it’s fail every time I tried. This is my code :

https://myDiscourse.com/posts.json?title=New+test+posted&raw=new+posted+text+to+test+creation+by+api&category=45&api_key=xxxxxxxxxxxxxxxxxxxxxxxx&api_username=admin

I don’t know what is wrong, can you help me please?

Thanks