As dieFluggeister said, depending on the temp and humidity during construction AND at your location you will get wrinkles/bubbles. It sounds like you got one of the "worse case" planes. I have gotten one or two like that. Realisticly, it should take you 15 - 30 minutes to get everything corrected. Be advised that you will probably have to reshrink the covering every spring. Here in Connecticut I have to do that because the "hanger" for the planes is not heated.

If you can someone experienced to help you, that would be best.

If you decide to do it yourself. I suggest using the iron instead of the heat gun. The heat gun will cause the seams to shrink if you are not VERY careful. Be careful around the seams anyway (make sure they are sealed) and if you have any bubbles, take a pin and poke a hole in ONE END of the bubble, then iron towards the hole to release the trapped air and seal the covering back down to the wood.