There are several answers to your questions about managing your TriPress account :
How can I do to activate my account?
I noticed that registered users would be supposed to receive a mail in order to activate their account. Unfortunately, you may not doing this yourself since you will not receive this mail because of technical issues.
It’s why we recommend you to complete the registration form, then send me a mail by using my email address “firstname.lastname@example.org”. When I will receive your mail, I will go on website dashboard to activate your account. We will then send you a mail to notice you that your account has been activated.
Can I change my username?
It is possible for TriPress users to change their username. However, you may not doing this yourself. For doing this, you need to contact an admin and ask him/her to change your username. You may them ask him/her to change your old username for an username of your choice.
That has the advantage to avoid spam since TriPress users may not change their username as often as they change their clothes.
There will have more questions and answers gradually.