Then you will be led through the Q. First you have to enter you user name, chose a name for your team and you can invite other users to your team. Afterwards you are done and can start using Q.
The easiest way to log in to your Q. is to use the global Login-Page. Here you just have to enter your login details in the intended fields. Then you just have to click on the pink "Login" button and you will be in your Q. If you are member of more than one team you will be logged into the team you used the last time.
Another option is, to write the domain of your Q. directly in the address bar. Then you just have to enter your login details as well and you will be in your Q.
If you forgot your password, you can send yourself another one. You can look it up here, how you reset your password.