The description you gave of a readme is indeed a pain in the ass for players that just started adding mods to their game. I try to keep my readme's as clear as possible and in decent english. It's just that there are alot of non-english modders so you can't expect them to write in perfect english. I'm Dutch myself so my english isn't perfect either .
As for the mods not working, when using SparkIV did you hit 'Save' after you've imported the modded files? Have you also updated your game to 126.96.36.199. or 188.8.131.52.? Most mods are made for that first patch but mostely work for the latest patch too.
The easiest mod to try out is a weaponsmod, if you'd like I can explain in detail how to install one. Let's take one of my own for example (that way I know for sure that it works and it's not the mod that's non-functional) Just leave the sound alone for now and only install the weapon itself:
Now open up SparkIV and hit Browse, go the pc/models/cdimages and double click weapons.img. Hit the big 'import button' and select both the .wdr and the .wtd file that's in that package. When you've done it correctly the should be highlighted in blue, hit save if this is the case. Now just exit SparkIV and fire up your game. You can now just try out if it works, if you haven't got a desert eagle in game just use the cheat for it (dial 486 555 0100)
If it still doesn't work, do you have a backup of your game and is it possible SparkIV navigates to that one? If you want to know for sure that you have the right weapons.img just go the your gta 4 folder and go the pc/models/cdimages and right-click weapons.img and select open with .. and select SparkIV (probably not yet in the programs list so just browse to it).
Don't give up too quick, gta 4 can be alot of fun with mods