Blinking 3 led's in parallel?
Create a say 1 or 10 or 100 mS counter.
For each LED provide a count down register.
Each time the timer "ticks" decrement each LED count down register.
When a register reaches zero, process the LEd and reset the timer.
QED.

You can also use count up to a limit or other schemes. The key point is that each task is essentially independent with the single timer source driving them.



LEDRED = 7  
LEDGREEN = 12  
LEDBLUE = 20  

DO Until_hell_freezes_over

DELAY 100 mS

Decrement LEDRED  
IF LEDRED = 0  
    Toggle RED_LED  
    LEDRED = 7  
ENDIF  

Decrement LEDGREEN  
IF LEDGREEN = 0  
    Toggle GREEN_LED  
    LEDGREEN = 12  
ENDIF    

Decrement LEDBLUE   
IF LEDBLUE = 0  
    Toggle BLUE_LED   
    LEDBLUE = 20   
ENDIF   

LOOP