"on" a tour ? Why is "on" before " a tour"? How to use the phrase?

My first letter for Angelove Dear Angelove I am so sorry to write a letter for you until now.I am pleased to see that you are health and beautiful through a photo of the letter you sent me. You forgot to smile in the photo. That's ok. I also feel nervous when taking pictures every time.You have learned dance for a while.Do you like dancing? My hobby is playing drums.Maybe one day, you can dance to my drum accompaniment. All you think of is to enjoy your carefree time now. Take care of yourself and your family. Sincerely Angel

My first experience of high mountain climbing-Jade Mountain(Taiwan) Jade Mountain is the most highest mountain in eastern Asia. It locates in Taiwan. I am close to it but I have never seen it until the end of 2015.I joined a party to get a valid permit.I rarely climb mountain in daily life.Before climbing Jade Mountain, Many friends of mine told me that I should do exercises to improve my lung capacity and physical power.We should check our components of equipment. If it become a impromptu climbing, you will suffer the discomforts of travel. The common illness is altitude sickness. The mountain guide told us good methods to prevent altitude sickness.We should drink a lot of tea or salt water to supply electrolytes. My breathing should be deep and slowThe experience of Jade Mountain climbing is a preparation for going off to Tibet.I decided not to take any medicine for altitude sickness before this climbing. I wanted to test what reaction in my body.Through this opportunity I can more realize my body's situation. Finally, I went up the summit of Jade Mountain. Although thick fog covered Jade Mountain, It is still beautiful and magnificent. In the meantime, I totally understood that I had altitude sickness. There are many symptoms.I felt uncomfortable,headache and can't breath. I were really unwell at the second day.My footsteps were instability. I were exhausted and I did not want to go back . I determined to achieve the goal. Perseverance will push you keep going.You will be a resolute but you are still small in front of the nature.

The atmosphere of city is very mush polluted I don't want to do exercise outside today morning due to the atmosphere is so terrible.The weather news report PM2.5 of the atmosphere is over the standard.The index even is up to the highest degree. Doctors warn people not to go out if possible.The polluted air like poison gas.How to find out a proper way to clean up the polluted matter?or cut down on it?We should stop falling out with anyone at environment protection.I hope to have a breath of fresh air every day.

A colleague is capable of betraying your group A colleague has no professional ability, even does not obey the manager's instruction. Worse, He spread rumors and make troubles.I feel so angry. Thinking things from a different angle, This is a good training for me to realize how to treat persons like that in the future. I need to purge the mind of prejudices. I have to do meditation. Ps. What would you do, if you were me?