Christ is Risen!
This depends a lot on the jurisdiction/usage of the parish you are entering. It will also depend on the context of your first confession, meaning on how you are being received into Orthodoxy. In which case there may or may not be an absolution immediately thereafter.
If you are making a confession before or at the time of being received the nature of that confession will likely be different from subsequent ones. It may include some type of renunciation of heresy (very uncommon lately but it is possible). The retrospection you will be asked to undertake is something that the priest who is receiving you alone can answer. We cannot do that here.
If you are being received without confession and will confess only as the need presents itself in the future after your reception you would only confess sins as far back as your reception into Orthodoxy then from that time only as far back as the previous confession. Of course, you can mention sins if they constitute a pattern but the sin previously confessed and absolved is just that, gone; don't dig it up again unless there is a need for informational purposes. It was forgiven then it does not (cannot?) need to be forgiven again.
I think the brief outline Nick gave is useful, especially in the Slav practices. Confessions are not heard in a box but usually in the church at a stand with a Gospel book and a cross or icon and cross. In some places the penitent kneels in others he/she stands. I would add that there are somewhat standard ways of begining a confession in some jurisdctions and usually sorrow for the sin is expressed by something similar to an "act of contrition" or by a response to the priest's question. Of course, the very act of confessing indicates contrition and the priests are usually sensitive and the "form" is not so important if they want you to do something they will tell you. After the confession absolution is given by the priest placing his stole over the head of the penitent and pronouncing an absolution. A blessing is then given by the priest and the penitent kisses the hand of the priest. Once the end of the stole was given to me to kiss instead. Also, in the Russian usage oftentimes the priest puts the stole over the shoulders of the penitent and both lean somewhat over the stand with the Gospel, etc. during the confession proper. This seems to muffle any sound and is also a comforting comforting gesture.