How do move one post into another one posted in wrong category

Go to the post and in the upper right corner of the actual post you'll see a pencil. Click on that and you'll get a list of options. I think it's the third one that lets you change the category.

Were did ya see ma 1st post cant find it help me oup bro

After you've posted it, select the pencil icon. It should give you a menu, including the option to edit the category.