About purchasing customs

Hi, here in this community, could anybody or insiders tell some experience or tips about how buyers purchase the products they want?

For example, here in Houston, a company want to purchase textile products from home or abroad:

1.where would they get the seller' information?

2.And what kind of websites would they uaually visit or search for sellers?

3.Are there some other special ways to find the products they want?

I just list the three questions here and I believe it is not so simple about the purchasing customs or hobbies.

So hope some insider people can share your experience with us.

Thanks so much.

Marcus