Ok, since these people are getting all aggro with you let me try and help. You're wondering which notes to play when? Well that's too hard to tell, of course. And even if I gave you a bassline, you'd just be reiterating something I wrote.
I think a bassline should reflect the rhythm of the percussion line while bolstering the bottom ends of your chord progression.
So, let's say your chord progression was:
I - IV - V - I
You'd want at least the root on the first beat of each bar, so if the key was C ... the roots would be: C, F, G, C. In between that you can do anything really that fits in key. You could outline triads like C, E, G; F, A, C; G, B, D ... etc in a rhythm that meshes with your percussion.
Style and genre also dictate what happens between those notes.
Now, this isn't the be all end all, you don't have to have the root of the chord on the strong beat (First beat), you don't even have to have the root. But generally, that's what most untrained ears would find the most "logical", I think.
Though I say **** it and go with YOUR ear.
The only other thing I would say is not to let your bassline get too cluttered or busy, especially in mainstream dance or hip hop. It's hard to hear fast moving runs and what not in the lower register and it usually ensd up just sounding muddy and garbbled.