Helena-Ive never had any house cats as Im a total dog person. But, I will strongly suggest no tensil on your tree. Ive heard of many cats eating it, and it can cause serious problems and even kill them.
Listen to this lady, Helena!! When I was a young child my parents decided one year to put tinsel on the tree and one of our cats ate some and we had to keep pulling the strands out of it's bum We were lucky, because there's a risk of the tinsel getting tangled in the intestines, but our kitty was ok after. Embarrassed, but fine.
A precaution I have sometimes taken is to tether the top of the tree to the curtain rod at the window it sits in front of. 2 strings from the center of the tree tied to the right and left on the rod, that way if the cat climbs the tree, the only way it can fall is the couple of feet toward the window.