Ok, you must be a little confused seeing 3 addresses, you can copy any one of them. The smart reward 1 and Smart Reward 2 address are for monthly bonuses. If you have more than 1000 SMART in any of these two addresses, you get about 8% monthly interest (taken from the 25th to the 25th of each month)

For your spending address, you can use it as you wish but it is not elligible for monthly interest. So all you need to do is copy any of these 3 addresses and follow the instructions above. 🙂.