Welcome and congrats on your first day. What a great step to take.
You will find a lot of help on this site. There are many sober people who can share how they did it and help you out. We all had to start on day 1
For me, I went to AA, which really saved my life. It is not the only way, but it is the only way I knew how to stay sober.
Check out some of the posts by other newcomers. It really helped me to talk to others who were around my day count, because we all seemed to be going through the exact same feelings. There is a thread for the class of October which you may find helpful