Topic sentence and concluding sentence

" Until recently, people went to the store to buy what they wanted. However, now, you can enjoy shopping online. There are three reasons on line shopping is more convenient than going to the store. First, you don't have to go to the store to buy things online. What you need to do is to click tthe " order" button and input your credit card number. Even if you live far away from the store, you can easily enjoy shopping online. Youcan even buy goods from overseas stores online. Next, a huge variety of goods are available in online stores. Stores in the real world do not have enough space, so they cannot display all the goods they have .How ever, internet stores can display as many items as they want to. That's why online furniture stores and book stores are especially popular. In ther real world, furniture stores and bookstores require too much space. Finally, we can enjoy shopping 24 hours a day online. It iss OK to order things at 3 a.m. Many people are too busy to go shopping after work, so online stores provide an opportunity for busy people to enjoy shopping.Some people may want to see tge reak stire ti di sine research. Then they can buy the item they want online. In conclusion,online shopping is getting popular because we don't have to go to the store, we can see a larger variety of goods online, and we can shop 24 hours a day online. Online shopping will be more popular in the future because of these three reasons."

I guess , the topic sentence on the article above is " until recently, people went to the store tobuy what they wanted. However now, you can enjoy shopping online."
Then, the concluding sentence is " Online shopping will be more popular in the future because of these three reasons.?

I don't get used to do the paragraph writing exercise.
Could you help me ?