It only looks like a lot of work cuz there's a bit involved initially to get started, but once you get the hang of the process it really IS like riding a bike. There are three main file types for The Sims 3 custom content.

You might have to make the mods folder yourself if you don’t see one. Installation of custom content for The Sims 3 is covered extensively here, and in linked pages. There are several free tools you can download to do this. Just go into documents/electronic arts/sims 3.

In addition to that, you need to 'clone' original EA objects/clothes/etc in order to put your newly created CC in the game, as either a sims3pack or package file. Even something as simple as making new wall art requires one of these tools, that support DDS images (PNG images can be used instead, but only sometimes, I believe). Photoshop, GIMP and Paintshop, etc are essential to creating textures for objects. Blender is the only good one that's free, I believe. Milkshape and 3DS Max and Blender are the popular go-to's for creating a brand new object. The vast majority of object creation tools are all free, but some very important ones you have to pay through the nose for. In order to create objects you're gonna need several programs. I find it easier to start off with simple wall art creations or TS2-to-TS3 conversions, but some people can hit the ground running, from jumpstreet creating clothes and new meshes and all sots of wonderful new CC. I'm a big noob beginner and a slow and impatient learner, but those tutorials helped me SO much. I'm NO expert, so these were the tutorials I personally found SO helpful, I kid you not

How to content for sims 3