Does anyone have any tips or webpages that give good instructions?

I have planted several of these plants because they are fasting growing and provide lots of color. However, they are also rather invasive (depends on how you define fast and thorny. I do not want them to get out of control.

I am hoping to train them into a tall shrub ot even sort of a tree. Perhaps like a topiary with just the round or squared top section.

Nothing complicated. I just want to know when and how to cut the branches to keep it in check. Any suggestions greatly appreciated. smile