Getting a Scorecard
When you go to a baseball game, you'll probably see a vendor selling official programs for about $3 or $4. Outside some ballparks there might be a vendor who is selling an unofficial program for less. Programs are great sources of information about the teams and players that are playing that day. They also contain a scorecard. If you don't want to use the scorecard from the ballpark, you can buy a book of them at a sporting goods store. You can also create one, making it as simple or complex as you like. It's not difficult. If you prefer, you may download and use one of the simple scorecards that I created. If the simple scorecards are not adequate, check out the download page. You will find several scorecards that were sent to me by visitors to this site.
Looking at the Scorecard
Now that you've got a scorecard, take a look at it. There will be areas for different kinds of data, like game day information, batter performance, inning totals, and pitcher performance. Most scorecards will also contain an area to record a summary of the players' game performance afterwards. I didn't include a summary area on one of the scorecards I created, but creating a card of your own which contains one shouldn't be that difficult. The summary area should contain the following information for each batter: at-bats, runs, hits, runs batted in, and errors. Once you tally this information, you'll be able to compute all sorts of statistics.