A - Go to the IMAC web page and join IMAC (you will need to join the AMA too).
http://www.mini-iac.com/DesktopDefault.aspx?tabid=1
http://www.modelaircraft.org/
B - Download the 'Basic sequence' with the 'walk throughs'.
C - Download the judging criteria and read about each maneuver and how the maneuver is judged.
D - Practice the sequence. You can fly your foamie, trainer, the cheapest airplane you own... in Basic. There is NO limitation on the equipment you fly in Basic. Start with what you have now, upgrade later.
E - Go to a tournament, sign up to fly Basic.
F - Volunteer to scribe (record scores for the judges).
G - Fly when its your turn.
H - Do your best.
I - Ask questions.
...your started...
What is involved technically and financially with an inexpensive smaller size aircraft and, at the other end, an all-out, spare-no-expense 40 percent ship? For the smaller aircraft I will use a 25 percent scale CAP 232 that is made by Sig Manufacturing. This kit is one of the more popular ARF (almost ready-to-fly) kits. It has a wingspan of 73 inches and a ready-to-fly weight of about 11 pounds. ARF means the airframe comes pre-built and covered. All you have to do is some minor assembly, like installing the engine and radio gear. This CAP sells for about $350. The cost for a good 1.8-cubic-inch, two- or four-stroke engine is around $400. You also will need at least five high-quality servos, setting you back another $400. A simple $100 radio will work, but you are much better off spending the extra bucks for a basic computer radio ($400). So for a total of $1,550 you can be competitive in IMAC.
On the other end of the spectrum is a 40 percent (116-inch wingspan) CAP 232 made by Carden Aircraft. This is a kit in the more traditional sense, since you must build from plans with balsa, spruce, ply, and foam. The lower part of the fuselage is built up from these woods with formers and longerons as in a full-scale airplane. The front and rear turtledecks, wings, and tail group are foam core that is sheeted with balsa. The wings and stabilizer are removed for transportation. The cost of this kit is about $1,000. You will need another $400 just for hardware, glue, covering, and other nickel-and-dime items. This aircraft will need one of the 150-cc twin-cylinder gas monsters ($1,600). You need the best servos you can get and many of them. Typically that means three to four for the rudder, two for the elevators, two on each aileron, and one more for the throttle. That’s ii servos, and the best ones run about $115 each, totaling $1,265. Other miscellaneous items like a carbon fiber prop and spinner, servo leads, batteries, switches, etc. will add another $600. The total for this big ride is a little under $5,000, and that’s without the radio transmitter. Pilots who fly these 40 percent aircraft tend to buy the top of the line computer radio, so add $1,500. You could spend even more money and buy an all-composite airframe. That airframe alone can run as high as $5,000, and you still need the same items as the wood kit to complete it. To some this might sound expensive, but when I hear how much an MT or Hartzell three-blade propeller goes for, we look positively parsimonious.