Facebook offers an app for several smartphone platforms, including the iPhone. Using the Facebook app allows you to do many of the same things that the Web-based Facebook does, including post to walls. Facebook works to improve the app with occasional updates. Past updates have added features like posting to event walls, posting to places and a chat option. Keeping your Facebook app updated ensures you'll have access to all the most recent features.
Tap the "App Store" on your iPhone and open the search window. Type "Facebook" in the search field and tap on the Facebook app to download and install it on your iPhone. The official Facebook app is from Facebook, Inc. and is free of charge as of March 2011.
Tap on the Facebook app once it finishes downloading. Log on to your Facebook account with your e-mail and password.
Click on the "News Feed" icon at the top left and the "Status" button in the middle of the top bar. Alternatively, tap on "Profile" and touch inside the bar labelled "What's on your mind?" to bring up the "Status Update" window.
Type your post into the "Status Update" window and tap on "Share" to update your status and post to your own wall. Your friends and anyone you have allowed in security settings to see your posts will be able to read it.
Tap the Facebook app and tap inside the "Search" bar at the top. Type the name of the friend on whose wall you wish to post. The names auto-populate beneath as you begin typing.
Tap on "Write Something" at the top of your friend's wall. This brings up the "Wall Post" window.
Write inside the window and click on "Share" to add your post to your friend's Facebook wall.
Facebook has a website for mobile browsers, but it's more limited than the Facebook app.
You're not able to edit or delete Facebook posts from the Facebook app for iPhone, so check your post carefully before sharing.