Next Step

I last posted a thread of my 95 civic 1.6 not starting. Long story short there was no spark after the distributor, so I'm going to replace that, but there's also low compresion in 3 of the 4 cylinders, like lesss than half. I just need to know, what causes low compresion, and what I would need to do to correct the problem. Putting oil in them only raised the compression by 10psi. I was hoping I don't need to redo the heads, but if that's the case, what will I need? Pistons, Rings? Any feedback would be awesom, thanks.

It could be bad rings... or valve seals.... do a leakdown test.