If it is a V4, you'll have to wait untill the Travel Agency is fully made . If it is the V3, go to TamaTown, use your username and go to the Travel Agency on the Bottom Right corner of TamaTown. Go to the black computer screen with green words saying "LOG IN". Click it and it will ask you for your password. Enter it and press "Enter". Your tamagotchi will be given a code for the souvenier if you entered it correctly .