Re: I'm new and I need help
Welcome to the forum!
That prebuilt bike you linked to has the "chinagirl" motor on it, and they can be finicky. They require some TLC and varying amounts of maintenance. If you're relying on it to get around , you're gonna need to get very familiar with mechanical work. Mostly checking nuts and bolts all the time, but mounting and exhaust studs can break randomly. Since it's a motor-assisted bicycle, the bicycle itself is going to need extra maintenance, too. I see on that link you posted that bicycle doesn't have a front brake. If the pedal chain breaks or falls off, you won't be able to stop. The front fork has no provision for V-brakes, so you'd have to install a caliper brake - they don't do very well. It'll eat the paint off the front rim, go through pads quickly, and not do a great job at stopping. BUT, most of got our start on bikes like that, and the learning experience is invaluable.
A 4-stroke is gonna cost a lot more, depending on which way you go about obtaining one. For someone new like you, I'd recommend a Huasheng and Q-matic kit, but that's ~$650 not including a bicycle and you'd have to either build it yourself or have someone help you build it. It'll get better gas mileage, be easy to maintain, and be much more reliable tho.
Tough choice that initially must be made with your wallet. In the long term tho, you'll come out ahead with the 4-stroke, I promise.