A site with everything you need to know about the 555.
led strip
I wouldn't use 10 LED in parallel though, with a single resistor, the brighness is likely to vary between LEDs unless they are a perfect batch match.

Also, from 9V down to parallel Flexible LED Strip Lights will waste more power in the resistor than goes to the LED since the LED forward voltage varies from 1.8 to 3.3v depending on colour (red lowest, blue/white highest), Outdoor LED Lighting so for any colour, series pairs would be possible, while some colours would allow triples or even quads.

Alternately, go for a lower supply voltage, and 2 or 3 AA cells instead of the 9V.