questions about arrays and how to use them....

ok, heres my problem. im working on WG4 and i was looking at all the variables and the fact i have 21 seperate data files (one for each nation).
it would probably be easier if i used arrays, but i dont know really anything about them. how would i save them into a RA file? and do i have to declare or dim the variables i use in the array?


for example, right now i have this to save data:

for c=1 to 21 :c$=str$ (c)
open "war4-"+ c$ for random as 1
put 1,1,jt%:put 1,2,tr&:put 1,3,ps% (etc, etc)
close
next c


that method creates 21 seperate files to save the data. how do i do the same thing but only have 1 data file? im pretty sure arrays are the way to go, but need help figuring them out.