Assistance with adding custom characters?

[peproméno]

Hellooo there, I'm new here! 
Alright, right off the bat, I'd like to apologize for being a complete idiot. I am new to this all, and very confused, but I know a few things. I have been playing Smash Bros (whether it be Melee, Brawl, 4) for several years now, but I have just now realized the magic of modding. However, I suck at it. And this being the place I have retrieved my desired custom characters, I figured it was also the best place to ask this well, considering I have searched for hours for tutorials and other forms of help, but have found none useful.
Basically, I just want to (for the moment) mod in Galacta Knight in place of MK. (Found the mod here.) Buuut I'm honestly clueless on how. I have the Wiiscrubber, WinRAR, Dolphin, the mod files itself, etc. But I honestly am not positive on how to do it.
Any help, hints or tutorials are GREATLY appreciated. Thank you, and have a great day!! <':

[windhunter7]

It will be quite a while, maybe even a few years before I get my official tutorial up on how to install mods(But only ones that would replace existing files) with Dolphin, but basically, what you do is open up the Super Smash Bros Brawl .iso file with WiiScrubber, click the + on Data Partition 2, and then, browse for what file you want to replace(e.g. If you wanted to replace Link's red costume with a mod you downloaded, you would click the +'s on "fighter"->"link", and the desired file would be "FitLink01.pac"(For single-player modes) or "FitLink01.pcs"(For multiplayer modes)) and then right-click it, hit "Replace" and browse for the file you wish to replace it with. Note that it must be the same filetype, but not necessarily the same name. It does have to be a reasonably-short-enough name, though, or WiiScrubber will produce an error. Oh, and one more thing. When it shows errors when opening the ISO file, and after replacing the file, just ignore them all and hold down Enter. Also, it auto-saves after the errors, so just exit WiiScrubber after it's finished.

[peproméno]

Thank you so much!! You're a life saver

[windhunter7]

Sure, np!