It's kinda easy to miss on the new ugly theme, just type in that text box that's right under the "Profile Posts" button on your profile and above all other profile posts, then click the "Post" button at the bottom right corner of it. There are other ways to make profile posts, but that's the main one!
Are you sure? It's that part that says "Write Something...", bit hard to notice due to the color on the new theme though... if you are having trouble still, screenshot and show me how it looks for you and I'll help out! Another way to make a profile post is to go to the home page and look at the right side where it says "Recent Status Updates", then at the bottom of that little window it lets you post your own.