5 weeks? Your doing great. Just keep riding. If you can find some club rides, that will improve you. But some people don't like it.
Here are some things to think about, and some exercises to work into your rides.
First, as far as "technique" goes, most of us adults ride a bike like when we were kids. We just press down, left, then right, then left, etc. The pros call it "mashing" It has it's place, but there are more effective ways to pedal for distance.
"Pedaling in circles" allows you to use more muscles, and pedal faster (higher cadence) with what feels like less effort.
Think about the face of a clock. from 12 to 3, imagine you are pushing down on the acceleroator of you car, from 3 to 6, think about scraping gum off your shoe, from 6 to 9 thing about lifting your foot up a step, and from 9 to 12, thing about skating your foot forward.
Try these exercises.
1. Pedal only by lifting the pedals. Do not push down. Do it for as long as you can.
2. Pedal only by pushing and pulling (9 to 12 with one foot, 3 to 6 with the other)
3. Take one foot out of the clip, and pedal only with one foot. Change feet when you leg gets tired.
Do it for as long as you can once each ride. You will over time see that you can do these longer and longer, and pretty soon you will be pedaling in circles at 90 rpm and going 25 mph.
