Converted Clothing Keep Appearing Wrong

Sure! The package can be found here --> (http://simfil.es/127051)
the mesh can be found here --> (http://simfil.es/127055)
and the texture here --> (http://simfil.es/127056)

And if you can please explain to me what you did so that I can learn from this ^^

I'm not very coherent right now... but yeah, it was missing the uv_1. Only the legs were unwrapped. You can unwrap the skirt by selecting all of it, pressing U (like you would when unwrapping any uv map) and press Cylinder Projection. I tried it and it looked pretty good. Of course needs adjusting, but it shouldn't give too much trouble (hopefully).

The one that you must have installed is the 2.70. The 2.77 you need to download the zip versions (on the same download page), unzip it on a folder and run the exe.

femmejean sure! I'd like that as I get confused very easily :( Sadly due to my homework beeing too much I didn't really have the time to do something with this project today...I hope tommorow we'll have less stuff to do at home ^^

This is pretty long... I've tried to be as detailed as possible, and I apologize for any errors I've made. I still have much to learn about uv_1 maps but this is the way that I find the easiest. 

imgur album

1. The first thing I want to do is mark some edges and then split them. You should have a seam running down the middle in both the front* and back, along with the sides. You should also mark the seams on the bottom of the skirt as shown in the picture. This is needed in order to properly unwrap the uv_1. To split the seams, press CTRL + E, and in the dropdown menu, select ”Edge Split.”
*Actually, the seam running down the front might not be necessary, I do not know. I prefer to do it like this anyway to have everything split up.

2. Now that your seams are split, you can begin unwrapping the parts. I have selected the front right of the skirt by pressing L. To unwrap it, press U, and in the dropdown menu, select ”Cylinder Projection.” It should look something like this in the UV window. For now, you don’t need to move anything, because you want the parts to be level with each other before you start adjusting them. Unwrap the other parts as well.

3. It now looks like this. As you can see, I have moved the back parts to the sides. The ”right” piece (if viewed from the front) has been moved to the right, and the left piece has been moved to the left. This is because the uv_1 is mirrored. Only one half of the map will be placed in the actual uv space. As to why, I can’t say, but I will show what I mean in the next step. For now, it doesn’t look very pretty, right? That’s okay. On all pieces, I will select the vertices on the edge. To level them, I press S to scale, X to select said axis, and then 0. It will now be a straight line. Do the same for the rest of the edges (but make sure to unselect everything before you move on to the next, because otherwise they will align with each other, and that will muck it up.) As for the bottom vertices, you can select *all of them*, press S to scale, Y to select said axis, and then 0. All pieces will now be level.

4. It should now look something like this. See what I mean about it being mirrored? The left part, placed outside the space, should be identical to the right part. There are still tons of adjustments to be made, but you will have to make those after you’ve tested your item in game. As long as you don’t move individual pieces on the Y axis, you should be good to go.