That wikihow is complicated as F

http://www.hamuniverse.com/shortwaveantenna.html

I think you will have to do some research of the frequencies you want to pick up on as the length of them relates to the actual wavelength.

The Standing Wave Ratio needs to tie in as I remember, at full, 1/2 or 1/4.

No local hams about where you live?

Part of studying for the licence helps you learn about the antenna requirements. Different antennas work for different frequencies. The size and height from the ground are all factors. It's not as easy as just plugging something in in a lot of cases. The advanced licences get into this in detail. You need that licence to get onto more HF bands that will let you communicate globally. The Technician licence is pretty limited. It's mostly UHF and VHF which are line of sight. If you don't have a nearby repeater then your range is going to be pretty limited. HF lets you bounce signals off the ionosphere and get beyond the curvature of the earth limitation of other frequencies.