"Since" usually refers to a reference point the the past. "I have been studying English since high school." For usually refers to a duration of time. "I have been studying English for two years." However, they can both be used to give a reason for something, as well. "Since it's raining outside, I'll stay home and watch a movie." [Since + reason] always comes first in the sentence. The formula is [since + reason] --> [result] "For" is similar except that it comes later in the sentence, and is usually used with actions. The formula is [action + for] --> [reason]. "I'm saving money for my trip to China." There are actually other ways you can use these words, but these are the most common. If you'd like to ever set up a short lesson for [since/for] or any other grammar points, let me know. :)

since = pricised date in the past . Exemple : We have lived in this town since 2000 look ; (last year, 1992...) for = perdiod of time . (two years, four weeks...) I have learnt English for four years.

Hi, since = for a specific time in the past until now. For example : I have been studying Turkish since 2009. For = length of time For example: I have been studying Turkish for 3 years. I hope this will help you.