Thanks for contacting me with regards to your order. I understand that using resistance bands can be strange at first. With resistance training generally the strength comes from inner the cord itself. Unlike weights you don't feel the tension straight away. We have recently added a booklet to all our resistance bands, to make sure that customers get the most from their training.
Firstly, you're training with resistance bands, you can increase resistance by shortening the length of the cord. If you look in the poster I have sent (below) named squat bicep curl. You can see that I have looped the band and I am standing on both ends of the resistance band. This shortens the band, you can do the same with lots of different exercises.
Also you can do this by standing with both feet on the resistance band. Widening your stance with both your feet on the band will shorten the distance of the band between your hand and foot. This will increase resistance. I hope this makes sense.
If you have a resistance band set you can attach more resistance bands to the handles. Resistance bands can be tricky to use at the start but one you get used to them you can do lots of different exercises. I suggest try some shortening see how that goes.