hi,
Hmm, there were alot of threads about it on the forum. You may just use "Search" from the left.
I have elaborated and programmed such boards many times. The base thesis is that refresh rate must not be less than about 75Hz (I use 100Hz) per one bright step, otherwise flicker effect appears. Now calculate yourself: if you need with 16 steps of bright then you need to program timer for 1200Hz etc.

As you do not ask code so I try show you it by words (=

One of my projects uses 8 bright scales and I use one byte for each LED as control one. Each bit of control byte indicates must LED be turned On or Off at current refresh cycle (0...7). (In fact, there are two bytes there, another one is used for blink control, but let explain with more simple way). For example, when control byte contains 10101010b then it means that 50% duty cycle (meander) is used. Indeed, 11110000b produces the same bright but with bad uniform.
I have a little lookup table for the each of 8 scales and corresponded subroutine which accepts input numbers 0...8 (0 - off, 8 - max. bright) and translates these numbers into control values.
From other side, timer0 runs at 1000Hz and its ISR executes each 1ms. It takes refresh cycle number (with modulo 7), produces corresponded mask (from 00000001b upto 10000000b) and then ANDs this mask with the each control byte step-by-step. Each such operation produces zero/not zero state. All states are collected and then utilized as control LEDs groups (one byte per one group of 8 LEDs).

It may look hard but, in fact, is simple programmed.

Regards,
Oleg