you have a what they call an nylon acustic guitar what evr you do dont put steel strings on your guitar as the tenson will damage the neck and prob brake it stick with nylon strings if you need to change them your friend has a steel strung acustic guitar. In my opinion what you have a nylon strung acustic is better for new players easier on the finger tips.

Your friends guitar and yours are both acustic. there are diffrent types of acustics but in general there are classical,folk,beveld back and so on but i would imagine with out seeing it you have a classical nylon strung acustic and your mate have a steel strung acustic.

the 10 and 13 and so on you mentoned is quite simple here is a little tab with them in to show you. the numbers reprisent what fret to press.the tab below we will start with the bottom E (the fat one lol) press the fret on the 11th fret and pluck the E string then hold th 11th fret on the B string and pluck the B string.Then hold the E string on the 13th fret and pluck the E string and so on.

Top tip if you see a tab like the one below where two of the strings are on the same fret just bar them with your finger.put your index finger on the E and B string on the 11th fret and dont take it off then when you get to the part you have to press the 13th fret on the E string just use your middle finger to press it down while keeping your index fingers where they are.

E||---11--------13--------11---------------|
B||--------11--------11--------11----------|
G||-----------------------------------------| And repeat
D||-----------------------------------------|
A||-----------------------------------------|
E||-----------------------------------------|

I think you can pay via mail by sending a check to the site the info is on the site somewhere and there is a post on just the same thing somewhere. but if you do join via check or simmilar i think its $30 for 6 months as you have to join for 6 months due to admin and all of that but it will be worth it.

Currency is dollars.
hope this info helps ya