You need to be trained up on a number of traits to craft anything for sets.

elderscrollsonline.wiki.fextralife.com/Set+Bonus+Crafting+Locations

That link gives you the crafting locations in all three alliances for picking your sets or mixmash of sets that you want for your builds.

It is a lot easier if you already have a master crafter or even a half decent crafter toon, but if you do not want to learn the traits necessary to do your own, which imo is way better, then many crafters are around in zone, or guilds or your friends list.

In terms of level, try doing a set or mixmash of sets for every 10 levels, turn it green or blue, that should do you till you rank up in increments of 10, worth also putting enchants on if you can craft them or buy them if you want.

When you come out of the intro, you are level 3, so not really any point doing sets early game, unless you know someone or have an alt that is high level who can do them for ya.

You will find loads of items for the crafts that you can research, at any level though, and providing you have the mats and style, you can craft your own.

Good luck and happy gaming.