Red LED Fader help

I'm building this (https://www.electro-tech-online.com/custompdfs/2009/01/473-click_here_.pdf) for an art project. I've got it built and working, but unfortunately I need it to be brighter. So far I've got some LEDs with brighter luminosities, but that's pretty much the end of my understanding. I would guess that I need to supplement some of the components to deal with a higher voltage to power more LEDs.

Any help would be appreciated

What about just connecting another two LEDs plus 100R resistor in parallel?

i have no idea. i've never done anything like this so i'm very much so a newb

The base voltage of the transistor goes up to +6.5V. Its emitter goes up to 5.7v. Each red LED is about 1.8V so 2.1V is across the 100 ohms which is an LED current of 21mA.

Higher power LEDs have a higher voltage so the dimming will not be correct unless a higher battery voltage is used which will cause the transistor to get hot.

Use a 12V supply with 2.5V high power red LEDs.
The base of the transistor will go up to 8.7V. If the max LED current is 60mA then the transistor dissipates 198mW which is warm, not hot. The emitter voltage will go up to 7.9v and the current-limiting resistor will have 2.9V across it. For a max current of 60ma the resistor value should be 2.9V/60mA= 48.3 ohms. Use 51 ohms/one-quarter W.

could i get you to clarify so that even an art major could understand (because i am one, lol). Thanks a bunch for your help

I said what needs to be said. If you don't understand Geek-talk then do Art instead of Electronics.

that is, in fact, exactly what i'm doing this for