um set ur game up as 2 vs. 2 in the beginning (game setup) and have ur ally be a moderate comp too.
however, comps are kinda dumb and u'll learn more just by playing 1vs1 on mod, then hard, then try vs. u vs. 2 hard comp til u can do that, then 3, etc. i'm working on 3 hard comp. right now. my rating is somewhere between 1650 and 1700 right now to give u an idea of the comparable online skill level to vs. comp skill level.
if u can't beat a comp on moderate 1 on 1, do NOT try playing online u will just get whooped and discouraged. play a bit of online once u can beat a hard comp 1 on 1. then watch ur losses (they will prob be losses at first) to see what ur opponent did against u. try learning those things against the computer until u DESTROY a hard comp (not taking advantage of the AI) in say 15-17 min. then try online again. now u'll win some games. again, watch what ur opp does on ur losses. try these vs. two hard comps til u can beat both of them pretty easy. play online, now u'll get to 1700 and start getting beat.
repeat, repeat, repeat.
fh