Help me get my way around chicago!!! =)?

ok. so im going to the rascal flatts concert tomorrow july 18 at wrigley field. i know i have to take the metra train to ogilvie then go to the red line and take it to addison.. BUT... i dont know how to get from ogilvie to the red line...... i am walking.. not taking a taxi... so does ne one know how to get there!!!??? please help. thanks in advance!