I've written before that the best form of training follows this process: Tell them what you're going to do, tell them what you're doing, tell them what you did.

When working with your software company to report bugs or other issues, you should follow a similar process:

1. Tell them what you were trying to do. For example, "I'm trying to process a membership order."
2. Tell them how you did it. For example, "Here are the steps I followed." Be as explicit as possible and include screenshots!
3. Tell them what happened. Show the results of your steps (again, including screenshots).

We've all heard "a picture is worth 1,000 words." I mentioned screenshots twice above for that very reason. Screenshots often communicate more than any narrative can.

"The membership join process doesn't work" is reporting a bug, but it's almost useless in terms of helping the software company figure out your problem. But following the process above will clearly communicate the issue and bring a resolution much more quickly.