This page explains how to play the game. It covers many aspects you'll need to know and should be read before starting your adventure for the first time.
Explore the World
Mother is an RPG, so expect exploring to be a big aspect of the game. The game takes place on a large map called the field (or overworld) where all the towns and landmarks are located. The landscape is also littered enemies, as well as caves and dungeons where enemies reside. Unlike EarthBound, Mother's encounters are random, so you'll have to wait and see which enemies you face!
Collect the Melodies
The whole point of playing Mother is to collect the 8 melodies, located all over the world. Melodies are usually found in the field using the Check option (but there are some exceptions). When you find all the melodies, you'll be able to face the final boss. They're pretty much the whole game.
As you move from town to town, it should be important to note that each town has shops and hotels. They provide you with services that can help you on your adventure. However, like all good things in life, these things cost money. Unless you have a decent supply of cash, don't go overboard on the purchases.