In the early '90's, I had justonly been workeding for severala few years, and my younger sister lived with me.

Comma between independent clauses. Never put an apostrophe in a decade name (60s, 70s, 80s, 90s). A lot of English speakers actually don't know this ;)

She didn't have a job, and the clothing store was mainly for her.

I got married back then, so wthe three peopleof us ran the store together.

This version sounds more natural to me.

We bought clothes fromon Hanzheng street in Wuhan, in Hubei province.

Always use the preposition "on" with streets, avenues, roads, etc.

To save time, we usually takeook the night bus to Wuhan.

To protect the passengers, the bus owner hired a strong man holding a thick iron stick sitting on the front door in case the robbers came.

"Robbers," not "the robbers," because you're describing any robbers who might show up, not specific robbers.

It was said that some people in some areas in Henan province would rob the bus during the night, though I have never experienced that situation.

More natural: "though that had never happened to me."

Maybe afterAfter about three years, my sister got a job, so we closed the store.

Sounds more natural.

I have ridden a bicycle for about one year.

This makes it sound like you've been on the same bike for a year nonstop. I would say, "I've been riding my bike for about a year."

Sometimes I almost don't want to get off itstop.

Sounds more natural.

I once tried walking, but I doidn't think my legs could stand it.

Keep tenses consistent ("tried" = past, so "didn't" should be past, too).

My legs often hurt if I walked a littlefor too long.

The phrase "a little long" isn't really used.

My first bicycle iwas a stable -speed common bicycle.

"First bicycle" implies that you've had other bicycles since then, so I'd use the past tense.

The one I was riding recently is a variable speed one, and I have other variable speed ones, too.

From your response, I know we are both happy people and have smart points towards life.

Not sure what you mean by "smart points towards life?" Maybe "wise attitudes towards life?"

This attitude is very precious that nothing can compare.

I understand what you're saying, but this sounds unnatural. I would say, "This attitude is invaluable."
Invaluable = extremely useful; indispensable

(I don’t intend to join competitive cycling because I am not a young man, but if there is competitive cycling for old people, I don’t think I will decline wouldn't turn down the opportunity.)

Sounds more natural.