edit: wow really sorry, im struggling with comprehension lately. Click on Buy BTC at the top left main menu. Down the bottom in yellow does it say "Create new offer to buy BTC with xxx" where xxx is the currency/account you have setup? thats the button you need to hit to create an BTC buy offer...just make sure you have created an account in your local currency in the account page, and in the settings page your currency is the preferred currency.
may want to say what currency you want to buy in/what country you are from so that others can help.
There is a final confirmation screen, if the currency is not correct...quite simply... DO NOT CONFIRM it. Its plain as day what the offer you are creating is. So if its wrong and you cancel it you will lose the 0.0005 free or whatever it is.