Okay I got your message(: so it depends on whether or not you updated your app.
If your app is updated, you're going to press the little person button on the lower right hand corner. Then there should be a "post an update" button on your screen, it's orange. If you can't find it, scroll down a bit and it should be right underneath the part that has your bio.
If your app isn't updated, press the 3 bars in the top left corner to open up the menu. Then press the dark gray area around your icon, it should take you to your profile. From there it should be the same, just search for the post an update button and if you don't see it right away, scroll down a little bit.
Let me know if you need some more help okay?