I've been reading from J.J. Fux's "The Study of Counterpoint" and I have the first species down and understood but i'm having trouble understanding the fundamentals of second species. I get that the first half note follows the same rules as 1st species and that the second half note can be a consonance or dissonance (only by filling in two notes that are a third apart) but I guess what I need help understanding is how do I go about choosing the interval of the second half note from the whole note in the Cantus firmus? and how do i lead it into the next bar following the rules of motion?

I know that probably seems hard to understand but I hope someone can help me out X(
<Raven> I got so baked last night
<Raven> that I WOKE UP high o_o
<Raven> Do you have any idea how euphoric that is?
<Raven> I felt like I was being born.
Approach and leave dissonances by step.

Apart from that, do what you please to get to the next measure.
so like the rules about which motion to use dont matter or what?
<Raven> I got so baked last night
<Raven> that I WOKE UP high o_o
<Raven> Do you have any idea how euphoric that is?
<Raven> I felt like I was being born.
Well you still should be avoiding your parallel / hidden 5ths and 8ves (they should be a full measure plus a beat apart, while there are some circumstances that you can get away with fifths: off strong beats as passing tones) but apart from that you can create melodies as you wish. Contrary motion is better, as always.

There are some guidelines / rules about the melodies, though. Don't be combining leaps greater than a third in he same direction, after large leaps it's better to change direction, and so on. Your melodies should be singable and sound good when you do.
right, ok. I think that answers my questions thanks
<Raven> I got so baked last night
<Raven> that I WOKE UP high o_o
<Raven> Do you have any idea how euphoric that is?
<Raven> I felt like I was being born.