You'll need to go to free agents and import historical players.
From there you need to choose the database that you downloaded from spritze and then you will be prompted to enter the lahman ID of the player you're searching for along with some other information.
If you are unsure of the lahman ID of a player search for them on baseball reference.
Oscar Charleston Recognition Page - Baseball-Reference.com
that is Oscar Charleston's page, the "charlos99" is his ID.