Wa alekum as Salam wa Rahmutal Allahi wa Barakatu
Congratulations that you started praying brother, I am really happy to know that =)
First I want to tell you something very important in case you don't know, prayers for men are to be offered in the mosque and not at home, if its hard for you at the start then first try to go for al Fajr and al aishah (there is a GREAT reward for praying them in congregation) and then gradually you will attend all in the mosque inshallah.
About the other prayers (nafl prayers), they are prayed just like the obligatory prayers, some of them are before, some after and some before and after the obligatory prayers.
Start little by little, don't start praying all at the beginning or satan will work with your self to lead you astray. But there are nafl prayers that you should make sure you don't miss. Let me give you a brief.
1 - 2 rakahs before Fajr (Don't miss!!!) - The Prophet pbuh says these two rakahs are better than the whole world and whats in it. If you go to the mosque and the praying already started then pray these 2 nafl rakahs after the fajr prayer.
2- 4 before and 2 after zuhr
3- 2 after maghrib ( dont miss)
4- 2 after al aishah and then pray 2 rakahs (shafh) and 1 rakah (witr) (don't miss)
That's only a brief, there is more, I advice you to see this website, it shows all and the rewards of each, but don't get too greedy and do all at the start^.
http://jannah.org/madina/index.php?topic=3856.0
Jazak Allah Khiir brother
May Allah help you and get you closer to Him inshallah, ameen