Common Emitter, can't understand how collector current is found
You are right.  At DC, the collector current is the current thru Rl, which is (Vcc - Vc) / Rl.

Parts of what you snipped were cut off, but maybe the part you quote is talking about the AC characteristics.  Note C2.  It holds the emitter a at 0 V for the purpose of AC analysis, below some frequency.

Put another way, this circuit has higher gain at AC than DC.  The equation for the AC component of the current thru Rl is different than that for DC.