Right or wrong this works for me. Listen to the song thru your CD player or what ever you have. Tap your finger on the table top, tap your foot on the floor, strum across your shirt with a pick - as you listen. You want to hear the BEAT of the song. Hear the bass? Hear the rythem of the song? That's what you want to hear. The "boom" of the bass will be the downsttrum - what you don't hear between the bass "boom" will be the upstrum. Here is some strum patterns you can use. These are all 4/4 timing.
D = down
U = UP
D - D - D - D.............count 1 - 2 - 3 - 4 - 1 - 2 - 3 - 4 - 1....
D - D - U - D - U - D - U..count 1 - 2 - & - 3 - & - 4 - & - 1 - repeat
D - U - D - U - D - U - D - U...count 1 - & - 2 - & - 3 - & - 4 - & 1 - repeat
(the above patterns are just a few that you can use)
These should get you started BUT you have to be able to hear the song in order to understand the strum pattern. Print out the song showing the chords. Look at where the chord changes are and pay attention to the WORDS that the chords change on. Feel the beat of the song - get that foot going as you keep time to the music and count in your head. Try this and let us know if it helps.
Nela