Small Engines (Lawn Mowers, etc.): sears riding mower, model numbers, transmission fluid

Question
i know nothing about this mower. it was given to me last week. ok, it is kinda old also. so, i got it to run/idle but it doesnt move/go. is there some trick to putting it in gear? or maybe some place to check for transmission fluid? i dont even know where to start looking. any help would be great! thanks  p.s. its a sears LT 10 36

Answer
 Hello Erick:

 Can you seen me the Model Numbers Off the Mower, Please. They should Look Something like, "520.xxxxxx" or something similar. With these Numbers I can Locate a Breakdown/IPL and Better Assist you. Thanks.

 Respectfully

 John