Hi Helm!
I think you are still a prospect and not officially a member of a team, but I am not in charge of handling 2D prospects, so I could be easily wrong.
If you are afraid that your email hasn't been read you can try to resend it with the "receipt of reading" option, that will send you a little message when the receiver of the email will eventually read it.
If you have to upload the task in Nexus, I guess you have to explore a little bit the website.
However, I don't know which is the common procedure used in these cases, so check back with the person that assign you the task.
If you have further trouble you can try to contact that person that assign you the task through IRC on the irc server irc.freenode.net, channel #planeshift.