This trophy is titled "Wanderer" and it's for completing your first player match. These are found in the network tab and can be either searched for or hosted by players. The community is fairly dead at this point in time, so it's suggested you have a friend on hand to play a match with you. This isn't the only trophy tied to player match, either. There is also one for 150 player matches played, so find somebody who will be willing to play for more than just a little bit.