If you are curious now, I suggest you don't do this.

First, you have to understand 3ds.

MAX or maya, preferably 3ds.

MAX, because maya has too few suitable plug-ins

Then, according to what clothes you make, you decide whether you want to know about modeling software such as zbrush, painting and mapping software and so on.

You need a solid foundation to ensure the quality of the above software. If you only study for one or two years, it is ok, but it is generally not very stable. Usually there will be various problems in the game, such as flashback, crash, computer explosion, asteroid hitting the earth and so on.

Then learn nifskope, simple, and if you study hard, it will take about a week.

These are the things you need to make an ordinary dress.

Making physical clothing is the rational use of HDT physical system. There are tutorials in the forum of 3dm, which can be produced in a short time with nifskope.