there are a number of ways to accomplish the same goal in most programs.
like said above by fyre, he hit it right on the head, but i'll elaborate for you.
u can use the lil sequencer in FL to sort of map out how u want your drum loops
you'll be using your mouse instead of a midi controller for this method
1.go to the step sequencer, select pattern 1 this will be your first drum pattern, make it 8 bars for an 8 bar loop, set your tempo and click the metronome. make sure it's set to pattern mode.
2. pick the track on the step editor that has your drum, highlight the bars until you get a nice drum pattern going.
3. go to the track with your snare or clap sample, insert the claps or snares where you want them, don't get too fancy yet, save that for when you start progressing your beat.
4. now, you can either add some highhats or begin a melody. to work out a melody i would start on a seperate 8 bar pattern, so now you should be working on pattern 2 for this.
5. go to the play list window and insert 1 bar on pattern 1 and one bar on pattern 2. pattern 2 may look shorter so you'll have to go back to the step sequencer and extend it for 8 bars. now put fl studio in song mode and press play.
insert a vst instrument and highlight the steps as you did with the percussion. click on the piano on the upper right corner of the step editor so that the piano window will open up for that track (this will not be the piano roll). you should be looking at a verticle piano that shows up for every step in the 8 bar loop.
5. take the melody in your head and break it down. if it's a 16 bar melody you can put the melody on two different patterns or extend the pattern for 16 bars instead of 8.
6. you'll have to punch in the melody one note at a time, changing each note on the verticle piano. if you play by ear like me, you may have to hum your notes out loud while your finding the right key.
7. at this point you should have a nice 8 or 16 bar melody with an 8 bar drum pattern. you can now build up from this by selecting another pattern which should be pattern 3 depending on how many patterns you used for your melody.
8. going back to your play list assuming you have an 8 bar pattern you can extend that four times just to give you a little play room for you to switch it up a little.
9. now highlight one 8 bar pattern selecting that 8 bar pattern for every track and copy it over, you should have a verticle pink line extending about 4 tracks down so now your song should be five 8 bar patterns long unless your melody was 16 bars it would be 9 8 bar patterns long. the 5th or 9th bar should have track 1.
I have to bounce so i'll be back to finish later tonight. better yet, i'm going to put together a video for you.
